Timber framed house - improve insulation

NickNickleby · 24-02-2021 6:43pm #1

Greetings,

This is a very general question really. Mother bought a house in the noughties and I believe it's timber frame construction. I base this on its age and the fact that all walls sound hollow, even the gable wall. A couple of years ago, I had to install a second handrail on the gable for going upstairs. I cut the plaster board to see what was behind it, to figure out how to screw the rail safely to the wall. It seems that there is a concrete wall - presumably block of some sort. I also had to cut a hole in some polystyrene which was about 50mm thick. This polystyrene was loose, not stuck to the wall. The other thing was that an awful draught came through the newly cut hole. No problem, I made sure it was all airtight again when I was finished.
I was always surprised that this house wasn't warmer, given that it's modern enough, and aren't all modern homes now the bees knees in insulation. (My tongue is now firmly planted in my cheek). So, if I wanted to improve the insulation in this house, what would the options be?
My own home is a 70's cavity block house, with internal insulation added. I can't imagine that would be an option in my mother's.

The fact that I know nothing about the construction methods used in TF houses is probably pretty evident, but it's my understanding that all houses since about 2000 have been built this way.

I'd welcome comments just to aid my understanding.

Thanks everyone!

MicktheMan · 24-02-2021 8:08pm

Doesn't sound like TF construction to me but rather a standard enough concrete construction (which was quite poor wrt heat retention).

Imo, your first port of call should be to find out how exactly the heat is being lost.

NickNickleby · 24-02-2021 9:09pm

Hi Mick, and thanks for the reply.

Right so, did a bit of googling and if I understand it correctly, a timber frame house could be assembled and be totally enclosed in timber on the outside and plaster board on the inside, and the frame holds all this together. Then the external leaf is added, which could be brick or whatever.

So, in my mother's case, would it be unusual to have wind whistling round behind the plaster board? If the plaster board is completely airtight, I suppose what happens behind it shouldn't matter. (or should it...

).

But if this is rogue air, my thought is that the air vents should be a tube from outside to inside, and the gaps around the tube sealed, so any air passing through the tube is not allowed to go between the blockwork and the plasterboard. Does that sound right? If so, I'll take off a few vent covers and look for that.

mike_2009 · 24-02-2021 9:29pm

The air vent is a good place to look all the way "through" the wall and determine the construction. Mine is cavity block on the outside with timber batons on the inside - dry lining on this (which is plasterboard with plastic backing - vapour barrier) and fibre glass between the batons - 50mm.
The draught I get is from the gaps behind the plasterboard, between it and the wall - it's totally open to the attic, nice channel all the way down the inside of every wall in the house...!
Options to upgrade I got:
Cut 300mm strip out of middle of plasterboard on every outside wall, pull out all fibreglass insulation, spray foam into this space and reapply plasterboard, plaster and paint / repair.
External Insulation
If you have a cavity call (that's if it's not timber frame) then you can look into getting the cavity pumped. I can't as I don't have a cavity, the square holes in the blocks are all offset in the wall build making it impossible presumably to fill them all evenly as they don't line up.
You can always go for external insulation anyway which could help with the draughts but some basic air tightness testing would help identify the worst culprits and be money better spent tackling those first?
My air vents went a grill on the inside and it was completely open to the outside grill on the outside of the wall, no tubes.
Anyway, getting a really good professional to advice is a must, taken what I've said with a grain of salt.....

MicktheMan · 24-02-2021 9:30pm

NickNickleby wrote: »

1. So, in my mother's case, would it be unusual to have wind whistling round behind the plaster board?

2. If the plaster board is completely airtight, I suppose what happens behind it shouldn't matter. (or should it...).

3. But if this is rogue air, my thought is that the air vents should be a tube from outside to inside, and the gaps around the tube sealed, so any air passing through the tube is not allowed to go between the blockwork and the plasterboard. Does that sound right? If so, I'll take off a few vent covers and look for that.

1. Depends on the wall makeup but no it would not be unusual in either a TF or concrete built to have airflow at the back of plasterboard.

2. Does matter. What happens at penetrations of the pb (sockets / switches) and at junctions?

3. Rogue air? You are correct about the wall vents. However, back to my first point, what is the wall makeup? If the block work is untreated (i.e. bare) then this block work is more than likely a sieve so doesn't really matter what's happening at the vents if the walls are allowing copious amounts of air to pass through the structure / house. This is the reason why I mentioned "quite poor" heat retention in previous post.

MicktheMan · 24-02-2021 9:36pm

mike_2009 wrote: »

You can always go for external insulation anyway which could help with the draughts but some basic air tightness testing would help identify the worst culprits and be money better spent tackling those first?

I agree on the testing for air tightness and addressing these weaknesses but be careful if you think EWI will help with air tightness, in the vast majority of cases it has no impact on its own (despite what the salesman or glossy brochure might tell you!).

mike_2009 · 24-02-2021 9:39pm

like I said engage the professionals - I've spoken to too many sales people!!

Dobloman · 24-02-2021 9:45pm

It might be a 9" cavity block with drylinning on inside.Fairly common type of house construction in the 80s,especially in the Dublin region. Is there timber battens fixed to the block work and then plasterboard fixed to the battens.

NickNickleby · 24-02-2021 9:50pm

Thanks guys, lots to think about there.

So, a concrete block wall could be a sieve - even if its rendered on the outside??

Rogue air. hahaha I was lazy. I meant unexplained (in my mind) draughts emanating from behind the plaster board.

So, if moving air behind the plaster board is normal, then sockets etc, floor to wall joins etc will have to be absolutely airtight to keep this air behind the plasterboard.

Or... bear with me, I'm trying to understand... stop the air getting behind the plaster board in the first place.

So, if I check all air vents to ensure they're not leaking into the walls, fill in the tops of all external walls to prevent air from 'falling down' behind the plaster board, that should mean I'm applying the airtightness at the source so-to-speak.

mike_2009 · 24-02-2021 10:10pm

You may also have gaps around doors, windows, windows & door seals, floor joists penetrations, pipe penetrations, attic hatches and more if it's anything like mine?! You can get what's called a blower door test and use smoke sticks to see where the worst draughts are but I'm getting ahead of myself, but yes, getting all those draughts closed off correctly is going to really help improve the comfort levels in the house. A deep retrofit tackles these challenges head on but is not cheap and they really strip down the house so unlikely you'll live in while they are doing it. Lots more useless info but you're on the right track.....

tweek84 · 24-02-2021 10:12pm

Yes it is a timber frame house, is it brick on the outside by any chance?

These houses were built during the 80s.

The circulation of air between the timber and the block work is required so that the timber can breath.

Things to note the cavity cannot be filled, if you insulate the block outside it will have little effect as you need to have air circulation between the block and the timbers. Some simple ways that i found to reduce the draughts in this case is to make sure all sockets and switches are well sealed, take off window boards and insulate and seal the gap between the window and the inner leaf and replace window boards. Another thing you could do that was mentioned to me was to seal around the bottom of the skirting boards, as most of the time the pasterboard slab does not reach the bottom of the floor and draughts seep in.
If you want to insulate there is alot of work involved, you have to remove the existing slab, remove the plastic membrane, remove the insulation (which is probably the proper itchy fibreglass stuff) then reinsulate, put in new membrane, seal all socket outlets, then put on an insulated slab and make sure it is sealed then replaster.

MicktheMan · 24-02-2021 10:21pm

NickNickleby wrote: »

Thanks guys, lots to think about there.

1. So, a concrete block wall could be a sieve - even if its rendered on the outside??

Rogue air. hahaha I was lazy. I meant unexplained (in my mind) draughts emanating from behind the plaster board.

2. So, if moving air behind the plaster board is normal, then sockets etc, floor to wall joins etc will have to be absolutely airtight to keep this air behind the plasterboard.

3. Or... bear with me, I'm trying to understand... stop the air getting behind the plaster board in the first place.

4. So, if I check all air vents to ensure they're not leaking into the walls, fill in the tops of all external walls to prevent air from 'falling down' behind the plaster board, that should mean I'm applying the airtightness at the source so-to-speak.

1. Yes

2. Normal yes, good no. Correct, seal everything

3. Not easy and without extensive deep renovation.

4. Yes ...... but you just (kind of) addressed 2 holes in the bucket but what about the other 10 (e.g. bare block work). But every little helps.

A heat loss survey including air tightness testing might not be a bad idea. It will answer all your q's and highlight the best approach for you.

MicktheMan · 24-02-2021 10:26pm

tweek84 wrote: »

Yes it is a timber frame house, is it brick on the outside by any chance?

These houses were built during the 80s.

The circulation of air between the timber and the block work is required so that the timber can breath.

Things to note the cavity cannot be filled, if you insulate the block outside it will have little effect as you need to have air circulation between the block and the timbers. Some simple ways that i found to reduce the draughts in this case is to make sure all sockets and switches are well sealed, take off window boards and insulate and seal the gap between the window and the inner leaf and replace window boards. Another thing you could do that was mentioned to me was to seal around the bottom of the skirting boards, as most of the time the pasterboard slab does not reach the bottom of the floor and draughts seep in.
If you want to insulate there is alot of work involved, you have to remove the existing slab, remove the plastic membrane, remove the insulation (which is probably the proper itchy fibreglass stuff) then reinsulate, put in new membrane, seal all socket outlets, then put on an insulated slab and make sure it is sealed then replaster.

Not sure it's TF tbh. OP said they opened a section of PB on external wall and saw block work. So PB on battens or dot n dabbed onto block work perhaps?

NickNickleby · 24-02-2021 10:45pm

tweek84 wrote: »

Yes it is a timber frame house, is it brick on the outside by any chance?

These houses were built during the 80s.

The circulation of air between the timber and the block work is required so that the timber can breath.

Things to note the cavity cannot be filled, if you insulate the block outside it will have little effect as you need to have air circulation between the block and the timbers. Some simple ways that i found to reduce the draughts in this case is to make sure all sockets and switches are well sealed, take off window boards and insulate and seal the gap between the window and the inner leaf and replace window boards. Another thing you could do that was mentioned to me was to seal around the bottom of the skirting boards, as most of the time the pasterboard slab does not reach the bottom of the floor and draughts seep in.
If you want to insulate there is alot of work involved, you have to remove the existing slab, remove the plastic membrane, remove the insulation (which is probably the proper itchy fibreglass stuff) then reinsulate, put in new membrane, seal all socket outlets, then put on an insulated slab and make sure it is sealed then replaster.

The gable and back walls are rendered, the front is bricks half way up, then from the bedroom window cills, its a kind of red tile to gutter level, then normal roof tiles on the roof.

The hall wall has polystyrene behind it, but there was no sign of polythene or any other type of membrane. I'm assuming the plaster board is fixed to battens between which is sandwiched the polystyrene.

Anyway, there'll be no stripping of walls. I'll just paper over it with €20 notes :pac::pac::pac:.

Thanks everyone, I've learned loads here today. The vents and floor/wall boundaries will be a start. Then sockets and switches to follow.

Timber framed house - improve insulation

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