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Insulated plasterboard project

Does what it says on the tin
Itsallaguess
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Insulated plasterboard project

#72754

Postby Itsallaguess » August 7th, 2017, 7:14 pm

I've started this thread hoping to attract a discussion on insulated-plasterboard, and the benefits thereof....

This is something I've been looking into, on and off, for a few years, as we've got quite a few exposed outer-walls that would benefit from being better insulated, and an internal solution of insulated plasterboard would give a good cost/benefit solution I think.

Currently, the walls I'd be interested in applying this to are plastered brickwork, on a cavity wall.

Apart from gaining some space back, for which to then lose again once the insulated plasterboard went back on to the brickwork I assume, is there any advantage to removing plaster from internal brickwork first, or would an application of the insulated plasterboard straight onto the existing plaster be OK?

Cheers,

Itsallaguess

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Re: Insulated plasterboard project

#72809

Postby dspp » August 7th, 2017, 9:40 pm

In my house I have generally just put the insulated plasterboard on to existing plasterwork using dot n dab. Sometimes the existing plaster was in such poor condition it was worth taking off, but more commonly not. I have a range of thicknesses from 12mm through to 60mm insulation (plus the plasterboard layer). The choice of thickness for me has tended to be more associated with issues such as doors close to exterior walls that might get buried, things like that.

Works an absolute treat in my opinion and the thicker the better. Some people whinge about the space loss. Personally if a room is (say) 5m wide and you lose 100mm on the outside wall that is 10/500 = 1/50 = 2%. Hardly noticeable in a main room, more noticeable in say a narrow lobby.

My heating bills are much lower than my neighbours, and I can afford to run the house at a higher temperature than they do in winter. Much less drafty if you seal properly. I also did underfloor insulation in the void space (rock wool between floor joists, pinned in place with chicken wire, all closed off with Tyvek or equivalent stapled in place.

In some areas you do need to do a few screw/washer fixings on the ins PB for fire safety purposes, i.e. to stop it all peeling off the walls and blocking egress routes in a really bad fire.

I am not brand conscious and generally my builders have used whatever/whoever their accounts were with.

(I also have some 100mm sections but there I used Celotex or equiv and normal PB on top.)

My house is a Victorian terrace and I am now almost at passivhaus levels of energy use. Not bad considering I don't run MHRV.

regards,
dspp

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Re: Insulated plasterboard project

#72834

Postby Grumpsimus » August 7th, 2017, 10:50 pm

The main problem with insulated plasterboard is the thickness of the insulation, usually around 100mm plus the plasterboard 9.5mm.

You can get plasterboard with aerogel insulation, where the insulation is only 10mm. The advantage being that you lose very little space in existing rooms. Aerogel is a superb insulator and also the lightest known solid. The disadvantage is that is expensive.

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Re: Insulated plasterboard project

#72852

Postby ClaudiusTheIdiot » August 7th, 2017, 11:47 pm

There's some discussion of internal wall insulation on the Green Building Forum.

Also, might be worth considering whether there is likely to be increased condensation behind the insulation, so for example you might take care to seal the joints to prevent humid air from the room leaking into parts that will become colder.

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Re: Insulated plasterboard project

#73693

Postby PrincessB » August 11th, 2017, 12:25 pm

Hello Itsallaguess,

Currently, the walls I'd be interested in applying this to are plastered brickwork, on a cavity wall.


Warning - Long post

You can have cavity walls insulated which is a far easier solution if it is possible within your property.

I had it it completely done on a 50's detached using the blown method - It cost about £600 for the whole house and was done in a day. I lived there for the next six years and never had a problem with it, it also saved its cost several times over in reduced gas bills.

There are some articles indicating that in very rainy areas (Scotland is often mentioned) there is the possibility of damp creeping across from one skin of bricks to the internal walls.

Another known problem is the injection method may fail if the builders have managed to drip mortar all over the wall ties, this can block the shredded insulation from fully filling the cavity.

I understand that early insulation took the form of polystyrene beads, the old house (insulated 1997) used something that resembled rockwool that was shredded and injected down a hose using large petrol powered device.

My current house is a mish-mash of walls from different times. The original two up two down cottage (1874) is solid brick while the two storey rear extension must have involved demolishing the single story kitchen in the 1970s and using a more standard unfilled cavity - These were filled a couple of years ago with the same yellow shredded insulation and have again been problem free.

The rear extension is built to modern standards and has a double skin of breeze blocks with associated insulation put in during construction. I have some regrets in doing it this way as the internal walls of the new build were plasterboarded and then skimmed and I wish that for a little more money I had specified internal brick walls with wet plaster to finish.

While this might seem a bit moot, the plaster connecting to internal brickwork would have provided a greater thermal mass which would have assisted in moderating the room temperature between day and night. I'm still really pleased, I'm just annoyed I didn't think of this as it would have been better.

Finally on to the internal wall insulation which I've had done in the older part of the house.

One of the more readable guides is here:
https://www.homebuilding.co.uk/internal ... nsulation/

Also have a look at this one:
http://www.ecotherm.co.uk/Download.aspx ... =Eco-Liner

Link will take you to the Ecotherm datasheet which provides fitting instructions and importantly the different insulation levels of the different thicknesses of the insulation. We used the 37.5mm thickness boards which have a U value of 0.57. When using U values for insulation levels, lower is better and some common material values are:

Solid wall (two bricks thick) 2 or higher - The homebuilding guide states 1.4 which I think is wrong
Brick - empty cavity - brick 1.2
Brick - insulation - brick 0.3
Windows single glazed 6
Windows older double glazed 2
Windows modern a rated around 1
Doors vary, my wooden front door is rated at 3

It is important to understand that a U value describes the insulation level of an entire surface, so each layer has its own value and the U value is the sum of each layer. While the plasterboard I used has a value of 0.57, when combined with the double skin of brick which also insulates (admittedly poorly) the two together provide a value of 0.5 which is where I was aiming.

You'll also notice that as you increase the thickness of the insulation, you run into the law of diminishing returns, while the 100mm of insulation on the thicker boards is better than the 25mm of insulation I used, it's not four times better.

With that in mind, you can aim for different thicknesses of boards and as another poster pointed out, you can use the thinner stuff if it avoids the expense of moving a door frame or simply won't fit.

You don't say whether you are planning to do the work yourself or were going to use a contractor. My personal advice if using a contractor is to know all of the details of the job you are asking them to do and see if they tell you they are going to do them without prompting - Unfortunately any fool can dot and dab some plasterboard to a wall, the devil when using this stuff is in the detail.

Some points to look out for would be.
The correct fitting using dot and dab is to run continuous beads of adhesive top and bottom of each board while paying particular attention to the window areas - The last thing you really want is to blow cold air from the underfloor void into the cavity behind the plasterboard - they should know this.
If there are any voids between the panels and the floor, they can be foamed before the skirting boards go on.
Any moisture will condense on the coldest part of a room and this could lead to problems later on, we had the upstairs floorboards lifted and the voids by the walls loosely stuffed with rockwool insulation. On one wall in the living room, the insulation boards butts onto an internal wall.

Using my infra red thermometer - great things, everyone sells them, here's one:
https://www.labfacility.com/gm300e-infr ... gKK__D_BwE

If I check the temperature between the insulated wall to the left of the chimney it reads 21ºC in the corner, then internal wall just inside the room is still connected to the single skin of brick and the first few centimetres are a couple of degrees cooler - This won't cause any problems on a warm day but I expect that gradient to increase during winter.
That said, I've got a few places like this in the house and they are yet to cause any problems.

Another problem is internal doors - I spotted the main ones into the various rooms and the minor repositioning of the door frames was quoted for, I missed the door that leads into the boiler cupboard and was left with the original door only opening half way prior to adding skirting board and had to pay a joiner to narrow the door and partly rebuild the door frame.

On that subject, check your pipework. Any pipes too close to the walls will need to be moved at extra expense.

You will of course have to have any power sockets, light fixings or light switches removed and replaced - I moved as many these as made sense onto internal walls.

Radiators will need to be removed and re plumbed.

You could if you wanted to minimise loss of space remove the plaster to bare brick and then put the insulation board onto the brickwork - This is worth discussing to see if they outline the options to seal the brick behind the insulation, if they don't mention it be wary. It is also an incredibly messy process and the dust goes everywhere.

If you do use this option ask how they are going to do it. My preferred solution would involve a very patient labourer with a hammer and chisel, if they plan on using power tools they run the risk of damaging the brickwork badly.

My plan is to spend yet more money on breathable transparent paint for the outside walls, this should allow moisture in the brickwork to evaporate out while reducing the amount that gets in during periods of harsh weather.

You know as I write this, I begin to wonder why I bothered. Unfortunately while I like living where I do, the older parts of the house became difficult to heat and uncomfortable during winter it served as the only option. I am in a detached house so have considerably more outside wall than a Victorian terrace, the narrow nature of the plot made external insulation impossible and external insulation has its own set of problems.

To close, I was hightly interested in the homebuilder report (first link) which indicated that a great part feeling too cold in winter is due to excessive air leakage through the house. I question this as I think the reason you feel cold even in a warm room is because it takes hours to warm the walls up. In the meantime, I'm going to experiment with some of those smoke matches plumbers use to see if I've got unwanted draughts.

HTH

Regards,

B.

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Re: Insulated plasterboard project

#85727

Postby PrincessB » October 4th, 2017, 4:12 pm

An update.

It has been pretty mild so far this year so I'm not using much heating yet.

Having had the work done, the difference in temperature is amazing, with no heating on at all we've been finding the upstairs bedrooms to be somewhat too warm.

On energy readings - Before any work, my Daughter had a very nasty dose of flu and took to bed. It was February in the South East so night temperatures were no worse than -1ºC rising to about 6ºC during the day. We had to leave the heating on 24/7 with the TRVs throttled down for most rooms. We were using 120kw hours of gas per day.

Last weeks reading (7 days) showed we used 66kw hours of gas which apart from heating includes the hot water and gas hob.

I realise that at such different times of year with such different temperature and usage variants I am beyond comparing apples to oranges and my readings would be better described as comparing apples to bricks - On the plus side, were have been using 14 times less energy and the house is a more comfortable place.

I'll try to post a monthly update over winter if it helps.

Regards,

B.

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Re: Insulated plasterboard project

#85742

Postby tea42 » October 4th, 2017, 4:39 pm

In 1986 we added a Conservatory. It had dwarf cavity brick walls which we insulated with polystyrene sheets and I did the floor by shovelling in sharp sand which was levelled off and then floored with particle board with about 3 inches of blue foam stuck underneath it laying on the sand. The particle board was finally tiled. The Conservatory was made by Finch and was one of the first made from double glazed plastic in the UK. Its still going strong and can be used all winter with a small thermostatically controlled electric heater. Insulated board is an excellent idea, but I wonder about the joints and cracks appearing which seem to be a problem in timber framed buildings?

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Re: Insulated plasterboard project

#85786

Postby Itsallaguess » October 4th, 2017, 6:48 pm

PrincessB wrote:
I'll try to post a monthly update over winter if it helps.


I think that would be great PB, if you would, please.

Fantastic to hear that you've seen such good results. I think sometimes we can forget that when it comes to these matters, it's not just about any cost-savings that might be involved, but often the much more important matter of simply feeling more comfortable in our own homes, in all the rooms and on all the floors, even during winter time.

It sounds like you've now been 'given' comfortable access to your upstairs for a period of the year when you've not been used to it, and I think we can all sympathise with that position living in the UK, with much of our older housing stock suffering from the same issue.

Cheers,

Itsallaguess

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Re: Insulated plasterboard project

#92975

Postby PrincessB » November 3rd, 2017, 6:41 pm

I'll try to post a monthly update over winter if it helps.


The great news is that the indoor portion of this years project is now complete. The last of the decoration was finished yesterday to great relief. We should have opened a bottle of something chilled and bubbly, as it was we watched one of those property improvement shows and had an early night.

On energy terms, the smart meter is not smart enough to do a month by month reading so some of the figures will drift a day or two in and out of each month. They will all add up, I just don't have the time to take daily readings and tally them.

First set of reading are:
1st October to 28th October
Gas 590 kW-h (or the equivalent to)
Electric 207 kW-h.

To put the property into context, I've got a friend in a very modern new build penthouse flat (all electric) who claims to have never needed to use the heating at all. My old clunker of a house dates back to the late 1800's and unusually for the road is detached rather than being a semi.
Total floor area including extension is about 1200sq ft.

I'm quite impressed with the electric consumption which includes the normal ovens and washing machine usage. It also covers the heat pump tumble dryer, the heating in the main bathroom and a dozen or so high wattage old style bulbs.

One of the effects I was hoping for when installing the extra insulation was the retention of the heat from the lights and dryer to offset the demands on the gas central heating. With a poorly insulated house, heat is escaping through the walls so quickly you always need to use dramatic amount of heating to warm the place.

With excellent insulation, you have the reverse effect and in some cases might need to plan venting to remove excess heat from the building.

In this case, I've now got acceptable insulation and I'm delighted.

Regards,

B.

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Re: Insulated plasterboard project

#99020

Postby PrincessB » November 26th, 2017, 5:44 pm

Update time:

Second set of reading are:
29th October to 25 November

Gas 1096 kW-h (or the equivalent to)
Electric 244 kW-h.


Electric is up marginally, likely to be down to the extended use of the higher powered light fittings from earlier in the day as the nights grow longer and the need to use the 1kW electric heater in the bathroom for longer.

Gas usage has doubled from last months total which gives an indication of how the house responds by using more power for each additional degree of temperature drop.

Some of the following numbers are a little rough and ready, but a reasonable real world indication of insulation levels when applied to an older property.
In similar weather before any remedial work I've recorded 130-140 kW-h (or the equivalent of) gas use per day. On my 28 rolling average I'm using 40 kW-h (or equivalent of) of gas per day which is over three times better.

What has surprised me is how warm the formerly uninhabitable front room is and how quickly the (apparently) modern insulated kitchen/diner extension cools overnight. The difference is very apparent especially as I've turned off one of the radiators in the front room as the excess heat from the second radiator was confusing the central heating thermostat.

I'm also a bit niggled at how long it takes to bring the house to temperature in the morning and I now understand why some of these smart thermostats would be life changing in improving quality of life.

To add some context, some of the radiators are a very long way from the boiler and I have been told the feed pipes to these radiators should have been wider to gain maximum fast warming effect.

I would consider an intelligent thermostat with learning capability and we'll see what transpires over the coming year. I doubt I'll ever trust the security of an internet linked stat as it is becoming apparent that in an effort to get product to market, some companies are ignoring the security risks entirely and that worries me.

I think the main stat is out by a couple of degrees as my digital thermometer is always seeing -2ºC of what the stat says - Accordingly I've set it for 24ºC which now makes for a fairly consistent 22ºC in all rooms.

Let's see what December brings.

Regards,

B.

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Re: Insulated plasterboard project

#106857

Postby PrincessB » December 30th, 2017, 7:51 pm

December update time:

29th October to 25 November

Gas 1096 kW-h (or the equivalent to)
Electric 244 kW-h.


Current readings

26th November to 30th December

Gas 2126 kW-h
Electric 382 kW-h.

Considerably higher due to:
This is a five week reading as I'm working on the last Saturday of each month, November only had four.
It has been considerably colder.
#1 Daughter has been home since the 15th so we're using more heating, hot water and washing.

Some mini projects to do in the next few days include.
Draught excluder around the two attic hatches - One has a block of Celotex the other thus far does not - My feeling is that the draught excluder will slow air movement around the gaps and may make a difference. Whether a square foot of Celotex will make much difference is debatable, for a five minute job I think it's worth doing.

Fitting a keyhole cover over the mortice lock in the front door - It got lost somewhere in construction and you can feel the air whistling in as you pass the door.

I am not concerned at blocking airflow through the house a little more as the indoor humidity levels are fine. Rooms with humidistats are reporting around 50% relative humidity.

We've got extraction to the outdoors in the bathroom and gas hob in the kitchen while most of the windows have trickle vents built in.

I'll look at my energy provider next year, the tariff was set up with an old estimate of has and electric use - I'm now using considerably less gas while the electric bill has remained relatively static.

Here's to more things to try next year, regards and best wishes to all of you for 2018,

B.

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Re: Insulated plasterboard project

#113686

Postby PrincessB » January 27th, 2018, 3:29 pm

Update time

    1 Oct - 28 Oct


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