Old houses: Energy & insulation refits

[odysseus2000]

Hi dspp,

My family home is about 10x12 m, circa 1840, mostly suspended floors with a cellar & two bay windows.

We have doubled glazed, put 100 mm of loft insulation in & dry lined some walls & have gas/wood burner central heating.

If I burn wood all day during the winter it is just about tolerable. If I don't keep the fire burning all the time & if I wear two pullovers, two pair of socks & a jacket it's tolerable near the wood burner when running & I have my desk right next to it.

The house is coldest when it's windy & I believe some of this is from the wind pushing cold air into the house via the floor, so insulating the floor seems like a good idea. There is not much crawl space but enough & so I am minded to think of doing that.

Thank you for your most interesting & practical suggestions along with your earlier performance data.

Regards,

[dspp]

Our gable-end wall is quite a 'cold' wall, and bears the brunt of most of our poor UK weather, be that wind, rain, or often a combination of both...

It's such a large wall that I've often thought about the potential for over-boarding inside with one of the thinner (25mm/30mm) insulated plasterboards, but keep getting put off by the thought of getting the vapour-barrier side of things wrong, and embedding long-term issues into the wall.

If I've got a 'standard' brick cavity wall, with no insulation in it (I would prefer to insulate inside than bridge the cavity wall with insulation), and a standard plaster-on-brick, and then wallpaper-on-plaster construction on the inside face, are you able to describe the process from scratch with regards to the vapour-barrier installation and then over-boarding with the insulated plasterboard, especially with regards to the existing and remaining side-walls (that would not be overboarded), the ceiling (which is normal plasterboard) and the floor (which is wooden floor-boards)? It's often what to do at the 'edges' of the walls with regards to the vapour barrier where things start to look a bit risky to me, but I think this is due to my lack of proper understanding, rather than it necessarily being a tough aspect of the task...

I'd prefer not to use anything wider than 25mm/30mm due to space restrictions, but the installation procedure has always seemed fairly meticulous regarding the vapour-barrier side of things, and it's that single aspect that's putting me off this type of project, which I think would make a huge difference in comfort levels, especially during the winter.

Cheers,

Itsallaguess

iag,

You've already had good advice from PrincessBouncy and AsleepInYorkshire. What I am about to say may repeat some of what they said. You have three options:

1. Insulate inside: almost always using insulated plasterboard these days
2. Insulate outside: a combination of weather cladding & insulation & draught-proofing
3. Insulate in-between: cavity wall insulation

#3. CAVITY WALL: Wherever possible, on a retrofit I would avoid #3, especially if the wall is exposed to the weather. For newbuild I would hugely recommend this approach (using slab insulation) as it is the best of all worlds, but not so much for a retrofit due to concerns about a) how much insulation you can actually get into the right place; b) cost-effectiveness; c) long term performance as an insulator; and d) damp bridging. My house has a couple of walls that had early cavity wall build, but in practice this is so narrow and so cement scrap choked, that it is almost meaningless. Nevertheless a previous occupant 'benefitted' from one of the state-funded cavity wall insulation schemes using blown cellulosic material (waste paper in common terms) which frankly was useless at best, and counter productive at worst. Fortunately (!) the cavity in my place is so constrained that very little got blown anywhere and that has mostly disintegrated by now (20-years later).

#1. INTERNAL INSULATION: You are conceiving of this, but are worried about moisture which is a valid concern in some circumstances. If you already have moisture ingress into the room(s) from outside then you must address this on the outside before going down this route. If so you may find solution #2 the better way. However most moisture & damp concerns arise as a result of moisture that originates on the inside of the property as a result of human activities: living, breathing, sweating, washing up, drying laundry, whatever. As this meets the inside of a cold wall it condenses, and then mould inevitably starts, especially if it is in an area with stagnant air (such as the back of a cupboard). There are multiple approaches to this. Firstly get rid of the large sources of moisture - so put extract fans into bathrooms, hang laundry outside to dry, put extract hoods over cookers. You could eliminate the people but that would be counterproductive I fear. (By the way, I am assuming you have no damp coming up from below, if you do then that needs dealing with as well). l So then the next thing to do is to raise the temperature of the wall surface and this is most easily done by insulating the wall. For most situations use insulated plasterboard and a skim coat of plaster on top. Just take off the skirting boards; remove the window cills; pull off electric sockets & extend backboxes; remove old plaster & paper/paint back to a firm, dry, fairly smooth surface (that is a matter of judgement, but ordinarily means either taking off the existing wall paper, or in some cases hacking off the old loose plaster back to brick (etc)), and then putting on the IPB itself (dot n dab and/or mechanical fixation). In all cases you must eliminate moisture ingressing from outside (or rising) before you fit this.* For the insides of some of my exterior walls I went back to brick, others I went to firm plaster. I have never bought the IPB types that have a definitive 'vapour barrier layer', such as a metallicised foil sheet, as I don't think they are anything other than a marketing gimmick. The impermeability of the IPB comes from the cumulative effect of the PB facing, and the thickness of the closed cell foam behind it - so no need to add a foil layer (and the Gyproc data sheets say the same thing). After fitting then do a skim coat and refit electrics; build a new wider window cill; fit new skirting boards; and then decorate to taste. At the extremities of the wall I don't do anything special, except where I am butting up against a fitted cupboard where often the woodwork will need adapting (and the inside of the cupboard wall also insulating). In typical UK retrofits I am not hugely fussed about cold bridging - we are not doing a new build passivhaus, we are simply trying to cost-effectively improve old housing stock. Always fit as much as you can, but even 25mm of insulation and 12mm of PB (i.e. 37mm IPB) or less will make a huge difference. Aim if you can for 100mm. I always use IPB if I can rather than take celotex and then face it with PB. Why use two products when you can buy one that has been pre-assembled for you in a factory environment ?

#2. EXTERNAL INSULATION. I am afraid the tragic Grenfell fire has probably set the UK back a couple of decades as this really is the best way to deal with a lot of typical property types. It is fairly certain that Grenfell was the result of poor specification of the particular cladding system; poor installation of the cladding & etc; poor certification practices of the material; poor fire-prevention; and finally poor fire-fighting. BUT none of this is a critique of the concept of fitting external cladding per se, just a critique of fitting that particular cladding to that particular building in that particular way. I rather suspect that deaths due to ill health (cold/damp) over the next 30-40 years in the UK as a result of postponed/deleted cladding projects will exceed the deaths in Grenfell. So really I wish they had done Grenfell and others right first time. You might want to consider the low tech solution that most US/Canaa fixer-uppers adopt of putting battens on your pebble-dash wall (in itself a bad sign, as pebble-dash is ordinarily put there to address external damp); then put 100mm solid insulation (celotex etc) between the battens; then put a liner sheet over all that (Tyvek wrap or similar); then put cladding on that (either wooden 'clapboard', or vinyl siding to use the American terminology).** I am considering doing this on the external rear wall of my 'utility' block bedroom as the back of my house is not in the conservation zone, and that bedroom has yet to have any work done on it, and that wall is the lowest quality construction. If you do go this route then be careful with detailing around gutters and roofs and so on.

I am aware GS has asked questions about hot weather areas and I'll get to those in due course.

regards, dspp

* A typical product is this:
https://www.travisperkins.co.uk/British ... 9/p/519749
worth reading the data sheet:
https://www.travisperkins.co.uk/British ... datasheets

** see for example
https://www.oldhouseonline.com/repairs- ... insulation (be aware that you can ignore everything they say about insulating houses in the aircon belt (except GS who is in that zone)
https://www.google.com/imgres?imgurl=ht ... mrc&uact=8
https://www.google.com/imgres?imgurl=ht ... mrc&uact=8

[dspp]

Hi dspp,

...We have doubled glazed, put 100 mm of loft insulation in & dry lined some walls & have gas/wood burner central heating.

...The house is coldest when it's windy & I believe some of this is from the wind pushing cold air into the house via the floor, so insulating the floor seems like a good idea. There is not much crawl space but enough & so I am minded to think of doing that.

Probably worth you also increasing your loft insulation to at least 300mm, maybe more. Only 100mm is pretty thin. Personally I am happy to go to 500mm if I can. It is cheap and easy !

As you say there are a heck of a lot of drafts that come up through the floor. Some neighbours went the stripped floorboard route (just like me) and were appalled at how cold it became because of the wind whistling through the plank cracks. My way combines insulation and draft proofing, and works. Take care to leave a gap all around the outside edge so as not to wick moisture in from the external walls/ground.

Good luck.

regards, dspp

[PrincessB]

Thanks PB, I did forget to mention that the external face of the large wall I would like to potentially insulate is rendered with pebble-dash, so if this is important I'd like to say thanks for teasing this fact out.

Are you able to go into any details as to what you did at the 'edges' of your wall, where your boards came with integrated VB's?

By 'edges', I specifically mean the ceiling, side-wall corners, and flooring edges.

The builders we used were less than ideal and with relatively small rooms it was important to go as thin as possible in order to avoid having to move doorways much. Hence the decision to remove the plaster and go back to bare brick throughout.

In order:

Ceiling - Or rather the space between the ground and first floor - Floorboards lifted and the perimiter packed (loosely) with rockwool to a depth of about six inches.

Side-wall corners - There are only so many ways you can plop insulated boards into a space, in theory, you could shave them off to a 45º angle to butt against one another. In practice they were just put in at 90º in the corners. Same with the window areas which are complex but it works even without expert craftsmanship.

I was more concerned about the chimney breast which for practical purposes could not be insulated. If I use an infra red thermometer, you can see where the cold bridge is as the wall structure changes - In the real world, there's no damp, mould or any problems so far. There used to be, the front room (North facing) was pracically unusable outside of Summer no matter how much heating was applied.

Flooring edges - Floorboards were replaced so there's 100mm of solid insulation on a particle board flooring now covered with laminate. We did the whole floor area but did add a lot more ventilation to the underfloor area.

You've got cavity walls which should breath fairly well thanks to the air gap, if you've got no damp problems at present, I doubt a bit of extra insulation on the inside will cause problems - Just my opinion of course.

Regards,

B.

[PrincessB]

My family home is about 10x12 m, circa 1840, mostly suspended floors with a cellar & two bay windows.

We have doubled glazed, put 100 mm of loft insulation in & dry lined some walls & have gas/wood burner central heating.

If I burn wood all day during the winter it is just about tolerable. If I don't keep the fire burning all the time & if I wear two pullovers, two pair of socks & a jacket it's tolerable near the wood burner when running & I have my desk right next to it.

The house is coldest when it's windy & I believe some of this is from the wind pushing cold air into the house via the floor, so insulating the floor seems like a good idea. There is not much crawl space but enough & so I am minded to think of doing that.

Hi O2000,

Something that might apeal to you would involve replumbing the wood burner for a huge increase in efficiency.

I've never been a fan of wood burners/open fires or anything else that essentially chucks most of the heat up the chimney and requires a fresh and chilly supply to be sucked in through gaps in the structure.

Now if the wood burner had an air supply pipe that ran from outside the house into the base of the unit, all of that toasty radiant warm would remain in your house.

In my front room, I've got a gas fire which is designed to look a bit like a small log burner. It is rated at 5Kw input. The gas boiler is rated at 16Kw and while the gas fire is tasked with keeping a single room warm, the boiler has to heat the whole house to an acceptable temperature regardless of temperature outside.

I've got a smart meter, on testing, the single room warming gas fire uses more power than turning on the entire central heating system because most of the heat from the fire goes straight up the chimney.

dspp is worth listening too, in an old structure cold air will leak in regardless of what you do to seal the place up (within reason of course) the low hanging fruit are the underfloor area and the attic - These have already been highlighted.

Out of interest, are you detached and how do you charge your Tesla?

Regards,

B.

[odysseus2000]

Hi PrincessB,

Family home is semi detached, with the second half built after the first as servants quarters. We still have handles in all rooms that if rotated would ring bells to bring servants.

Yes, having a dedicated fresh air supply for the fire is potentially a good idea & one could also stick an heat exchanger in the chimney to recover some of the heat. Ideally one would also bring the cold air down via the escaping warm air to pre-heat it improve overall efficiency as is now done in many dwellings.

I have some wood land which along with discarded wood (pallets etc) provides my fuel via natural decay, I do not cut things down unless they die or are otherwise a danger. A silver Birch fell on the house last summer & kept me warm most of the winter as did dealing with the builders, although the insurance company were very good.

Re-Tesla I am a great advocate for the company & believe that their cars are the future. I have ample space for charging although I have 4 Volvos, 1 tractor & a Rover, only the last Volvo is taxed; rest are Sorned. But spending money on something new violates my prime directive of avoiding depreciation. I only buy cars once they have depreciated to a little above scrap value, so alas no Tesla car for me, but it is currently my biggest equity position as I encourage other people to have the best car & not to worry about depreciation which most people just accept as a fact of life. Interestingly my Grey Fergie tractor has appreciated in value by 4-6 times, which is a great return with similar on the ploughs, cultivator hoes etc. I only have one solar panel that I paid a tenner for with crazed surface, that I clear epoxied, but it still works & solar powers a shed. If I could get more second hand solar I might put them up, but new ones depreciate too much for me.

My other house is also semi detached & would benefit from under floor insulation & wall lining, but one can only do so much especially if depreciation upsets you.

Regards,

[dspp]

Thanks dspp, great post, and I have done a bit of reading on the subject over recent years so it doesn't all come as a surprise. It think one thing it told me is that I misread your post on the other board where you said your changes weren't costly and I wrongly interpreted that as meaning they were easy too. I now can see how exactly you achieved the economies so thank you very much for that explanation.

You are aware that we have purchased a commercial property abroad. This is in a location where heating and cooling are an issue and energy costs crucial, so I will be bearing in mind your post when we work on the property. [Additionally it has a problem with noise transmission, so any tips on soundproofing much appreciated.]

For our current property I don't think there is much we can do with the landlord. They are very wealthy and not bothered about energy consumption, just paying the bill whatever it is, and they love gadgets, hence we have an aga, heat pump, oil fired boiler, wood burner, immersion heated DHW tank (which we leave cold) AND solar panels, but minimal insulation and a one inch gap under the front door! (Mitigated by a second internal door.) It's a mess with, for example, the CH controls unable to switch the gas boiler automatically so it is rarely used. DHW has to be heated by the heat pump. And I haven't mentioned the electric fan heaters in the outside play room and a second heat pump in the "gym", neither of which we use much.

So why the high electrical consumption? As I said we heat the entire house for a good 7 hours daily and get all DHW from the heat pump. We have agreed to warm the whole house to prevent damp and mould formation and our rent is correspondingly reduced (LLs said their energy bill was c.£6000pa when they lived here). Is that enough to explain the bills? Here's more: There are very large double glazed windows in the living room and master bedroom. Windows are on the large size throughout. The footprint is L shaped so lots of roof and external wall. The 22mm pipe run from the heat pump to DHW tank is about 30-odd meters and water in the entire run both out and return has to be heated before any DHW heating or central heating occurs. And as you probably know when it's very cold the heat pump has to reverse and pump heat OUT of the house to defrost itself. It's all a nightmare TBH.

Thanks for the points about thermostatic valves. I kind of suspected that myself. Up to now our lifestyle has meant we mostly work in one of the rooms during the day, hence my thoughts about the valves. However, that room happens to be the kitchen area with aga, so we have simply run the aga all winter to provide core heat to the middle of the house (below kids' bedrooms) and kitchen. I wondered if we could get rid of the aga by using the smart valves for heating just this area.

To cap all of the above, the owners didn't want the PV panels on the roof so have put them at the end of the garden, where partial shade drastically reduces their function in all but the middle of the day. You wouldn't believe this but a major culprit is the meter/inverter board, which the installers have positioned where it can cast a reliable shadow on the panels in the early afternoon! Consequently the 4kW panels were only generating about 800W at 3pm (2 hours past zenith) today on a hot, cloudless day.

Bizarre!

GS

GS,

Regarding the UK house you rent and which you live in it all sounds like rather a nightmare. Unfortunately I am unable to add much value because a) I can't quite visualise it well enough; b) it is exceedingly complex; c) even if I could identify more actions you could take (apart from the ones I have already identified) then I am fairly sure from what you say that the owners would prevent you (just as with the ones I have identified). So if you think you are going to live there long term then the key issue is to have a heart-to-heart with the owners about getting a grip on things. Typical paybacks for interventions tend to be 5-10 years so you can see the problem for a tenant. Similarly for a landlord they spend the capital and the tenant gets the benefit, again problematic. Given that we are all short term tenants of mother nature this is the global problem of collective humanity writ small .......

Turning to your foreign commercial property:

Re accoustics: the way to address noise is to eliminate the source(s); increase the path length; increase the attenuation. Assuming you are unable to solve the source then you have path length and attenuation. For path length you can (for example) put an earth berm alongside a roadway, this has the effect of meaning sound cannot travel directly but must go up and then down to get to the neigbouring receptor. Since sound in this situation is a hemispherical propogation then pathway changes make a big difference to received sound level. For attenuation you can use reflectors, disruptors, and mass. So a brick wall on the berm would tend to reflect noise back towards the road. Planting vegetation on the berm (a hedge, or trees) would tend to disrupt and/or absorb (mass) the sound, and so to do the multi-layer wooden walls and foam sheets you see next to roads. Then mass is the great resolver: so thick concrete with air space gaps, or solid bricks and again airspace. In extremis you can go to engine-room sheeting (foam with a lead interlayer, very very expensive, limited lifespan). I'm probably not saying anything you don't already know, and the key is the local circumstance you are dealing with. In my factory I have got a noise reduction of -3dB to -6dB (that is reduced to between a half and a quarter of the starting level) by moving a noise source away from the operators, then by placing it behind a wall, then by giving the noise an alternative exit pathway. So little things together give results. Start by measuring and keeping records. Smartphone apps are fine for this.

Re energy: avoid getting into the situation you are in with your UK house. So first of all set up the tenancy agreements so you and the tenants have aligned incentives and some sort of co-gainshare. Secondly avoid getting into overly complex active technology technical solutions as the starting point. They may well be the final outcome, but do the simple things to start with. Concentrate on passive solutions to begin with - paint roofs white. Add insulation & reflect heat out. Add shade. Put thermal mass in the cool (so don't insulate the ground, that is something you do in cold places, not in hot places). And so on. Be careful with damp and aircon (https://www.oldhouseonline.com/repairs- ... insulation ) . Think about thermal management, solar gain, etc- when to have windows open, when to have them closed; north face or south face, roof or vertical, brise soleil. Etc. I don't know if you have energy security/continuity issues. Local regulatory things matter - is there a local FIT ? or net metering ? Can you run a private wire network ? Is your capital at risk if you upgrade a property ? So just some thoughts. If you have specifics then ask.

regards, dspp

[odysseus2000]

Happened to see this about aerogel insulation via one of the pop ups on the Lemon:

https://www.proctorgroup.com/products/s ... gJXmvD_BwE

It looks interesting in terms of its ability to provide good insulation in a small foot print and that it can be applied directly to wall surfaces with or without a vapour barrier.

There seem to be three downsides:

It is more expensive, somewhat mitigated by lower thickness that can save on socket, window frames etc adjustments

It is dusty to install, not clear whether once installed all dust hazard go away.

It is not as fire proof as other things like mineral wool.

Wondered if anyone had other comments to add?

Regards,

[PrincessB]

Happened to see this about aerogel insulation via one of the pop ups on the Lemon:

I've never dealt with it though I considered it an option for the reasons you suggest of not having to move doorways. We got away with not using aerogel by hacking the plaster back to brick and using that extra few mm to install conventional insulated plasterboard.

I admit to being an enthusiastic amatuer and while I can work with U values, or R values with a calculator, I don't know how to decode some of the bizzare (to me) numbers such as 0.002 or similar. You might be able to help with this

As I understand it:

Aerogel insulation is twice as good as the more conventional stuff - So if you need 100mm of rockwool or equivalent, 50mm of aerogel will do the job just as well.

It's made of glass, so I can't see how it would burn - The term aerogel is a catch all in a similar way to the word 'foam' which can mean all sorts of different compounds - Some aerogels might burn.

The glass aerogels are supposedly a pig to deal with. Do not touch without gloves, wear a respirator and even aerogel lined plasterboard can be tricky to cut with normal tools.

When I looked at it, it was expensive, at least four times the price of an insulated plasterboard panel.

Aerogel should be a last resort option unless you've got an impressive project in mind, or no space for anything else or so much money, you're stuck for a fun idea.

As a member of the dspp fan club, I'll echo comments:

Low hanging fruit first, unless you live in a stone barn, getting the roof insulation to spec is a must have. When I moved in to my cottage, I was impressed at the ceiling in the upstairs bathroom - Why plaster when you can paint some hardboard, or insulate the entire loft with more than a single roll of rockwool. The bathroom ceiling was about 3mm of hardboard and as Nigella Lawson would say 'Strewn' with insulation to add a decorative feel.

B.

[odysseus2000]

Hi PB,

My general feeling with insulation is that it is made as difficult as possible to confuse the purchasers so that a sales person can then flog you something based on the fog of confusion.

The best site I have currently found for comparing insulation and also some suggestions for how to e.g. do underfloor is:

http://www.superhomes.org.uk/resources/ ... -material/

But it is far from complete and illustrates the industry practice of sowing confusion.

In table 2 they show the depth of various insulations to reach a U value of 0.15W/m2k, but don’t mention aerogel.

By table 5 they finally get around to mentioning aerogel saying it has a K value of W/k of 0.013 and comparing to various other materials e.g. Kingspan Koolite and here it gets complicated as Koolite is said to have a k value of 0.02 -0.25. How they can be so confident that aerogel is 0.013 but so vague with respect to Koolite being worse by 2 to nearly 20 times escapes me.

The relation between U and K are discussed here along with r and c value:

https://insulation.org/io/articles/k-va ... e-c-value/

I would like to find a site that shows practical measurements of the various insulations, but so far I have found nothing.

The attractions of aerogel look fabulous but it is priced accordingly and it seems one can come within a factor of 2 with a much cheaper material. But how and what other trade offs there are is so hard to discover and in every case one is going to have to take the sellers word and then the skill of the installer, obviously best if self done, into account.

Still your remark of going for the low hanging fruit is the most attractive and I think that I will first go for the cellar which should be the easiest of all jobs save for adding more into the loft. In my experience it is the wind that really makes my house cold so I suspect that doing an underfloor job would be the best return for the spend. But am I misleading myself? According to table 1 of the first link, the walls are 35% loss, the ceiling 25%, the floor 15% and draughts 10%, saying the walls should be done first. But I am not sure why the walls would be worse under windy conditions making me doubt these percentages.

As I noted, there is huge confusion here and it is for this that the sales folk are trained to suggest stuff like underfloor heating (no chance of me getting that), heat pumps for being more cost effective and on and on. All of that wouldn’t work on me, but I am nonetheless far from clear as to what is best, suggesting that, as dspp mentioned, one should aim to insulate all 6 surface of each room and then one hits budget constraints, but having a nice warm house has positive health implications which ought to transcend budget considerations.

Regards,