Adding insulation to bedroom

[Clariman]

We are planning to remodel a bedroom and want to use the opportunity to improve insulation. Although the property is less than 12 years old, the insulation in one of the bedrooms is very poor. It is above the garage, has large windows on 2 sides and has the roof directly above and has external walls to 3 sides of the room. It has got very hot in this summer's temperatures and gets VERY cold in the winter. Putting it bluntly the insulation is cr*p.

There is some insulation under the floor (usual yellow stuff) and in the loft, but it doesn's seem very effective. So we'd like to take the opportunity of improving it as we remodel the bedroom. Any suggestions appreciated. More information and specific questions below....

We will be removing a small walk-in wardrobe's 2 stud walls and building another stud wall in a different place to create a much bigger walk-in. We will also be replacing the carpet with either a new carpet or a quality laminate. The guy helping us is a good designer but not a builder. However, he has spoken to an architect who recommends that we put Celotex on the floor before installing the flooring. Is this a good plan? It has a minimum thickness for 5cm so would that have to be installed under the floorboards rather than on top? If on top, then we'd have a 5cm (minimum) height difference between the bedroom floor and the hallway etc.

Also is there any benefit in putting insulation in the new stud wall? On one side will be the main part of the bedroom and on the other will be a very large walk-in wardrobe.

Many thanks
Clariman

[twotwo22]

I would have thought the easiest option with the floor was to remove ceiling in garage and install celotex from there. I would be looking to replace all insulation in there with celotex which should be a tight fit. Any gaps should be closed off with a spray foam. You would also need to check if a vapour barrier is required and which side of the insulation it should be installed. Or you could could have the whole lot spray foamed, though I think UK prices might be expensive. e.g. https://www.permasealuk.co.uk

Insulated plasterboard could be used in the room if you still need further insulation.

[pochisoldi]

I would have thought the easiest option with the floor was to remove ceiling in garage and install celotex from there. I would be looking to replace all insulation in there with celotex which should be a tight fit. Any gaps should be closed off with a spray foam. You would also need to check if a vapour barrier is required and which side of the insulation it should be installed. Or you could could have the whole lot spray foamed, though I think UK prices might be expensive. e.g. https://www.permasealuk.co.uk

Insulated plasterboard could be used in the room if you still need further insulation.

Pay attention to any required fire protection, specifically compartmentation (Building regs part B)
In theory you are supposed to get building regs approval for any change to "a thermal element", but

Thermal elements:
https://www.planningportal.co.uk/info/2 ... /47/roof/6

Fire safety (Section 5 Diagram 10)
https://www.gov.uk/government/publicati ... document-b

Of course in line with "when a tree falls in a forest and there's no-one there to hear it does it make a sound?", what answer would you give when someone asks "If I replace the ceiling of my garage while meeting part L and part B of the building regulations, and don't get approval, would anyone care?"

PochiSoldi

[Clariman]

Thanks both. Why are these things so complicated?

We would like to improve the insulation but these regulations, ironically, might act as an inhibitor to doing so. The only 'building' work planned is to take down one stud wall and build another, so that wouldn't require any approvals would it?

We will replace the existing carpet but that doesn't require any approval I presume?

However, while this is going on, we saw it as an opportunity to improve insulation. Hmmm.

C

[pochisoldi]

IMHO An internal stud wall separating two parts of the same habitable is not a thermal element. It still needs insulation so, for example you can have a warm bedroom and a cooler hallway.

Personally, if it was an "open front and back with no side door" type parking space, I'd go ahead and do it anyway. Any decision regarding a building regs application would depend on how long before I expect to sell up.

The extra compartmentation work could be as simple as using two crossboarded layers+skim instead of one, and gap filling using a different type of mastic. If you take this into consideration before you start, the extra cost could be negligible, and might buy you more thermal resistance anyway.

PochiSoldi

EDIT:
Just read that your stud partition is between the wardrobe and bedroom:
The "Do I insulate?" question has the same answer as "Are the two sides of the wall in the same thermal zone?"
I would suggest that they are in the same zone - I'd even go as far as to ensure that there was good ventilation between the two, otherwise the wardrobe could be the coldest part of the coldest room in the house thus becoming a target for any lingering humidity (even after boosting the insulation).

[PrincessB]

Hi Clariman,

There is some insulation under the floor (usual yellow stuff) and in the loft, but it doesn's seem very effective.

I'm sorry for the shortness of the reply but I'm about to eat.

Can you provide some further information on how hot and how cold the room gets?

I would be interested in whether the flooring feels cold in winter, how much use the room gets, the radiator power rating, if you know it?

We can tackle this from both directions, too hot should be reasonably easy to deal with while overly cold might require a bit more attention.

I'll respond over the weekend, this has been a really manic week. The more detail the better.

Regards,

B.

[dspp]

Clariman,

As a general comment do your best to get insulation in on all external walls, even (especially!) at the back of cupboards. Aim for 100mm, but it is worth fitting even 40mm or 20mm or 12mm if that is all that will go in. Insulating below, in floor will also help. I've successfully used celotex and the variant of insulated plasterboard on walls, sloping ceilings. Underfloor I use rockwool and tyvek.

Getting hot in Summer can be an issue. See my comments on the velux thread about that.

Ideally insulation should be on the outside of walls. Meanwhile in the real world in our own homes we have to put it on the inside of walls. That is why we get the hot rooms in hot summers problem.

regards, dspp

[Clariman]

Hi Clariman,

There is some insulation under the floor (usual yellow stuff) and in the loft, but it doesn's seem very effective.

Can you provide some further information on how hot and how cold the room gets?

In the recent hot spell, the room temperature has been over 25 degrees C. I cannot remember the highest figure. One winter we were away for 4 or 5 days and the central heating had failed while away. When we returned home, the room temperature was actually showing as 0 degrees C!

I would be interested in whether the flooring feels cold in winter, how much use the room gets, the radiator power rating, if you know it?

It is a very large master bedroom and we always sleep in it (unless away). There are 2 radiators but they are not very large. I don't know their ratings. Can I find out what rating they are? The room is carpeted so does not feel very cold underfoot - well I don't think so.

We can tackle this from both directions, too hot should be reasonably easy to deal with while overly cold might require a bit more attention.
I'll respond over the weekend, this has been a really manic week. The more detail the better.

Many thanks

[PrincessB]

Hi Clariman,

If I'm reading you correctly, the bedroom has four surfaces that face the outside world and the attic to make five which by default would make it the coldest room in the house while the two large windows are going make it too hot, thanks to thermal gain.

I have three suggestions for dealing with the heat.

First would be a reflective window film, admittedly from the outside, the windows will look mirrored but these films claim to block 77% of the heat which should make a difference.

This was the first result from the seach 'reflective window film uk' so the link is just to give you an idea:
https://www.windowfilm.co.uk/buy-online ... indow-film

Other options would be external French style shutters or the current trend of plantation shutters.

Second is to increase ventilation by installing some kind of fan with a view towards pumping fresh outside air into the room. There are a number of filtering induction fans on sale which pump air from the attic into the room below, they are marketed at allergy sufferers but might help you through a hot summer.

On that topic, my latest theory is that it's not the temperature in a bedroom that causes the greatest discomfort as people are not very good at knowing what the temperature is. Humidity and heat radiating out from warm dense walls are most of the reason it can be too hot to sleep properly.

My inclination were it my project would use a very quiet in-line bathroom extractor fan running in reverse to push air into the room. I would duct from the outside rather than the attic space (which could be red hot after a sunny day) and place the inlet vent in walk in closet area which would then duct to the main bedroom through louvre vents.

The third option is air conditioning, is this a step you would consider?

Now to the cold.

I take it from your earlier posts that you have lifted a floorboard and found the space between the joists packed with some kind of yellow rockwool type insulation?

According to the Screwfix website Celotex has twice the insulation value of rockwool so that option might appeal. Celotex is pretty easy to cut and handle and if installed well with the gaps sealed will prevent airflow from the garage area into the cold room.

On the subject of air ingress, a few pounds invested in a box of smoke matches (Screwfix or plumbers merchants) will give you a good idea of any problem draughts that might be ingressing into the room.

I'd spend some time with the matches by the power sockets/light switches and especially the windows. Anecdotally when I had my windows replaced the fitters showed me just how poorly the old windows had been mounted - They had left huge gaps around the windows and make it look acceptable with sheets of pvc so essentially what was between the house and the outside world was a couple of bits of thin plastic and some air, they had not even bothered to foam the gap.

I would assume the walls have a pretty decent insulation value as the house is so recently built, when winter comes you could use an infra red thermometer (£15) or beg steal or borrow a thermal imaging camera (£700+) which would show at a glance any cold spots. At a guess the walls are unlikely to be problematic, you've just got more external faces than most rooms.

There's another thread running on the benefits of upgrading the attic insulation.

Regards,

B.