Insulation / airtightness improvements following thermal survey

ZV Yoda

Hi folks,

Apologies in advance for the long post. We've just had a thermal survey / airtightness test done on our 15 year old house. Very informative & worthwhile thing to have done. Now I'm looking at fixing some of the issues raised.

The house is a cavity block 2 storey semi-d. The biggest problem we have is that cold air enters from outside under the eaves making its way down behind the internal plasterboard. As a result, we have cold air running down the walls & escaping at various places throughout the house (under skirting boards, electrical sockets etc). I’m not too well up on house construction, but from being up in the attic, I can see that top of the internal plasterboard is not closed off in any way & as such is exposed to the cold air. It seems logical to me that this should be somehow sealed off, but as I say, I’m no expert.

So, what’s the best way to deal with this? It’s very difficult to get access to the wall plate / plasterboard from the attic, but it might be doable. If I can do this, how should I address the problem?

If I can’t get sufficient access from the attic, could I address the problem from the first floor rooms by drilling holes in the plasterboard close to the ceiling & pumping in some low density expanding foam behind the plasterboard close to ceiling to create an airtight seal from the attic / eaves above? The risk is that the foam will just escape out the top of the wall & expand into the attic space.

A final thought is to remove the top 3-4 inches of plasterboard below the ceiling in all of the first floor rooms. Then fix a horizontal batten across the top to create a barrier from the attic, re-insulate the top section & then seal it back up (probably with coving to avoid having to re-plaster).

Any ideas on what’s the best approach to take?

BryanF

So you got an air-tightness test. Now get details prepared to show a contractor how to fix?

I would take off bottom 2-3ft of roof tiles and fix that way.

ZV Yoda

BryanF wrote: »

So you got an air-tightness test. Now get details prepared to show a contractor how to fix?

I would take off bottom 2-3ft of roof tiles and fix that way.

The airtightness test identifies the problem(s), but not neccessarily how to fix them (since they can be potentially addressed in different ways).

The problem is air entering behind the plasterboard. The answer is to stop the air entering. It could potentially be done a number of ways, hence my reason for asking for ideas about possible solutions.

When you say "take off bottom 2-3ft of roof tiles", then what would you suggest to actually fix the problem?

Calahonda52

ZV Yoda wrote: »

Hi folks,


The house is a cavity block 2 storey semi-d. The biggest problem we have is that cold air enters from outside under the eaves making its way down behind the internal plasterboard. As a result, we have cold air running down the walls & escaping at various places throughout the house (under skirting boards, electrical sockets etc). I’m not too well up on house construction, but from being up in the attic, I can see that top of the internal plasterboard is not closed off in any way & as such is exposed to the cold air. It seems logical to me that this should be somehow sealed off, but as I say, I’m no expert.

Yoda: a message from the dark side:
[can you post some pictures please of the underlined because you may have a bigger problem with insufficient horizontal battens as per fire regs. I say may, am not an expert.

Secondly, take off one of the wall vents internally and again post some picture of the construct inside]
End of message.
ps am happy to suggest possible solution once I have full intel on the problem.
I will be back once I see some pics: no pics, no back!

ct5amr2ig1nfhp

Can I hijack the thread a little...How much was the survey Yoda? Does the survey take long? Thanks!

Am very interested in getting a survey done as we seem to have similar problems with our house.

Calahonda52

Kairi Old-fashioned Underarm wrote: »

Can I hijack the thread a little...How much was the survey Yoda? Does the survey take long? Thanks!

Am very interested in getting a survey done as we seem to have similar problems with our house.

What is more important than price is

1. what was actually done
2. how the information was presented back
3. what improvements in A/T could the owner expect
4. what the estimated cost savings would be.

In relation to the camera work, unless the the guys know what they are doing it is often not much more than an expensive colour picture

ZV Yoda

Kairi Old-fashioned Underarm wrote: »

Can I hijack the thread a little...How much was the survey Yoda? Does the survey take long? Thanks!

Am very interested in getting a survey done as we seem to have similar problems with our house.

Hiya, No probs... I think he charges €300 ex VAT for houses up to 1500sq ft or €350 ex VAT (€430 inc VAT) for up to 2,000sq ft. I'd highly recommend it.

It was a thermal imaging heat loss and airtightness survey. He was here for about 8 hours. He sealed up fireplace / vents. He covered the front door opening with a rig containing a fan. This blows air through the house & allows him to use the camera to detect air leaks and / or insulation deficiencies throughout the house. He then did the same with the rear utility door.

At the end of the survey, we spent 45 mins discussing options for addressing the various issues. I have a CD ROM with a PDF document containing over 100 thermal images (and their corresponding "normal" images) of the entire house, so I know exactly which areas to focus on. E.g. there was a common theme throughout that there was colder air behind the plasterboards on external walls, leading to his suspicion that air was entering at the roof. We went up there to check & sure enough spotted the issue I described above. I'd never have discovered that by myself.

We also discovered there was little / no insulation around our bay window, that the fibreglass wool isolation in our walls was sagging by 12-18 inches at the top, our sunroom is excellently insulated, our attic is excellently insulated (I did this myself a few weeks ago), our windows are generally performing well, but 3 or 4 need seals and / or hinges repaired, the walls in our kitchen are poorly insulated, but the kitchen roof is performing well. All very useful info for us.

Of course, it’s horses for courses. E.g. for somebody who already knows a lot about construction / heat loss, then it may not worth the investment. I think it was money well spent.

ec_pc

Could you PM me his details, need a similar test done, thanks

ZV Yoda

Calahonda52 wrote: »

Yoda: a message from the dark side:
[can you post some pictures please of the underlined because you may have a bigger problem with insufficient horizontal battens as per fire regs. I say may, am not an expert.

Secondly, take off one of the wall vents internally and again post some picture of the construct inside]
End of message.
ps am happy to suggest possible solution once I have full intel on the problem.
I will be back once I see some pics: no pics, no back!

Sorry, didn't see your post originally. As far as I can make out, there are no horizontal battens & that would explain why the cold air is getting in behind the plasterboard.

Will try to get some pics tonight (although it's very cramped under the eaves in the attic). Would definitely appreciate any advice on possible solutions!

ZV Yoda

ec_pc wrote: »

Could you PM me his details, need a similar test done, thanks

PM sent

BryanF

ZV Yoda wrote: »

The airtightness test identifies the problem(s), but not neccessarily how to fix them (since they can be potentially addressed in different ways).

The problem is air entering behind the plasterboard. The answer is to stop the air entering. It could potentially be done a number of ways, hence my reason for asking for ideas about possible solutions.

When you say "take off bottom 2-3ft of roof tiles", then what would you suggest to actually fix the problem?

Epdm sealed to outer plaster leaf and inner ceiling vapour barrier layer.

ZV Yoda

Here are some pics to help explain.

We have an attic conversion, so I have to access the attic crawl space through the hatch in the dwarf wall (in the first pic). The rest of the pics are taken from within the crawl space in the attic. It's very tricky to get right under the eaves with the camera.

Detail.jpg and detail2.jpg are taken from directly above the top of the wall - hopefully you can see the problem. The cold air flows in from under the eaves & right down behind the plasterboard.

If I'm able to gain sufficient access from within the attic to the top of the wall (as in this photos) could I just pump in some low density expanding foam to seal off the top of the plasterboard? I'd only need the foam to expnd about 4-5 inches down behind the plasterboard. Any excess that expands too high above the plasterboard (potentially preventing cold air venting into the attic crawl space) could be trimmed off once it's cured.

Calahonda52

Thanks for the pictures, much appreciated.
Interesting construction indeed: be interested to see what the experts thin k.

I also asked about taking off the wall vents because while I see what you see in the attic, I have also remediated, either directly or indirectly, over 100 houses where the wall vents stopped at the inside face of the block work and the cold air from outside drives down inside the plaster board, creating the conditions you describe.

So before you start work, it would be good to identify all possible sources of the cold air ingress.

Thanks again for pics, it's nice when someone does what is suggested.

ZV Yoda

Calahonda52 wrote: »

Thanks for the pictures, much appreciated.
Interesting construction indeed: be interested to see what the experts thin k.

I also asked about taking off the wall vents because while I see what you see in the attic, I have also remediated, either directly or indirectly, over 100 houses where the wall vents stopped at the inside face of the block work and the cold air from outside drives down inside the plaster board, creating the conditions you describe.

So before you start work, it would be good to identify all possible sources of the cold air ingress.

Thanks again for pics, it's nice when someone does what is suggested.

No probs - I'm just glad to be getting feedback

I didn't get a chance to remove wall vents, but will do tonight. When the guy did the thermal survey, he removed at least one internal wall vent (that I know of - maybe he did them all). That must be what he was checking. Will double-check again myself this evening.

Thinking about it, I do know that the vent for the tumble dryer outlet in the utility room does not contain any pipe / tubing connecting the inner / outer vents, so air can come in from outside and run straight through the walls. Hmm… no wonder we’re feeling the draughts.

Irrespective of what transpires with the wall vents, given the pics above, wouldn't it be prudent to seal off the top of the plasterboard in the attic anyway? It'll be an awkward job, but I'd rather know it was done right.

Calahonda52

ZV Yoda wrote: »

Irrespective of what transpires with the wall vents, given the pics above, wouldn't it be prudent to seal off the top of the plasterboard in the attic anyway? It'll be an awkward job, but I'd rather know it was done right.

Yes you need to identify all such holes.

Yes re your proposal and the easiest way to do that is strip off the roof tiles and work from there, this allows eaves vents to be fitted to drive the air up by the felt and allows the being insulation to be brought right out to the wall plate, it also allows you to substantially increase insulation depth at the eaves , the rest can be done from inside.

However, I do have a concern about how that construction complies with fire regs.
I have never seen it done that way and am poking around attics since 1975.
The ceiling slabs in all the houses I have seen goes to the wall and acts as the fire break.

I maybe , and hope I am wrong ..

ZV Yoda

@Calahonda52 What you're saying makes sense about slabbing the ceiling first (so it creates a seal / firebreak from the attic). Then the wall gets slabbed to the ceiling, creating an airtight seal (after taping & skimming). Typical, the more I look into this, the less I like what I'm finding.

Any other comments / suggestions are welcome. I'll get some most pics posted tonight.

ZV Yoda

Here's some pics of the air vents. 3 of them have brown Wavin pipe connecting the inner & outer parts. The one for the tumble dryer doesn't (except for a tiny section).

All 4 vents look like they could do with some tidying up to prevent cold air getting into the walls, so I'll stick them on the "to do" list.

Calahonda52

Exactly what I expected.
The way I do them is clean them up, including the front pice of the pipe and then cut strips of airtightness tapes to fit from the pie to the plaster board, making sure that they are not too long so as to extend beyond footprint of vent.
The other thing to note is that expanded foam is not airtight of itself.....

see page 65 here for eave carriers
https://www.nsai.ie/S-R-54-2014-Code-of-Practice.aspx

it shows rigid insulation which I don't think works as well as loose such as cellulose

ZV Yoda

Calahonda52 wrote: »

Exactly what I expected.
The way I do them is clean them up, including the front pice of the pipe and then cut strips of airtightness tapes to fit from the pie to the plaster board, making sure that they are not too long so as to extend beyond footprint of vent.
The other thing to note is that expanded foam is not airtight of itself.....

see page 65 here for eave carriers
https://www.nsai.ie/S-R-54-2014-Code-of-Practice.aspx

it shows rigid insulation which I don't think works as well as loose such as cellulose

Cheers for that - it's great reference guide.

MicktheMan

OP, notwithstanding the firebreak issue as well as the air entering from the top, you also have the probable fact that air is also entering/exiting through the block wall itself because it is not sealed (i.e. rendered) internally.

As I see it, you can either try to seal all elemental junctions internally (e.g. wall to floor, wall to window frame etc) with proper air tight tapes, membranes, mastics or remove the internal drylining completely, render the bare block walls and externally insulate (by far the superior job).
Sealing the top of the plasterboard (if even possible) to stop air leakage may well be a wasted effort.

What specifically did the surveyor advise to solve this?

ZV Yoda

MicktheMan wrote: »

OP, notwithstanding the firebreak issue as well as the air entering from the top, you also have the probable fact that air is also entering/exiting through the block wall itself because it is not sealed (i.e. rendered) internally.

As I see it, you can either try to seal all elemental junctions internally (e.g. wall to floor, wall to window frame etc) with proper air tight tapes, membranes, mastics or remove the internal drylining completely, render the bare block walls and externally insulate (by far the superior job).
Sealing the top of the plasterboard (if even possible) to stop air leakage may well be a wasted effort.

What specifically did the surveyor advise to solve this?

While we do need to improve insulation & airtightness, the house is probably no better or worse than the majority of mass built homes in the greater Dublin area. It's all relative. So, from a cost and practicality perspective, removing all of the internal dryline & insulating externally isn't an option. We'd need to move out for a couple of week to do all of that. I'll be addressing the problems one by one from the inside.

Why do you suggest sealing the top of the plasterboard may be wasted effort? It's obvious the air is swooping right down behind the plasterboard. I was chatting to a building engineer last night & he also said the first thing he'd do is seal the top of the wall with a fire retardent foam.

Surveyor suggested a foam-based solution. At the time I wasn't sure if I'd be able to gain access from ther attic, so he suggested drilling the internal plasterboards a few inches below the ceiling & pumping the foam in that way. Or removing the top 3-4 inches of plasterboard, installing horizontal battens, filling with foam & then re-finishing.

Calahonda52

ZV Yoda wrote: »

1: Why do you suggest sealing the top of the plasterboard may be wasted effort?
2: It's obvious the air is swooping right down behind the plasterboard.
3: I was chatting to a building engineer last night & he also said the first thing he'd do is seal the top of the wall with a fire retardent foam.

1 & 2: I would suggest you ease off a little on the tone here, we are trying to help you here so read MtM's post in its entirety and don't bridle at the suggestions:) Nothing is obvious here:)

2: I believe the wall vents are a bigger problem than the top of the PB due to the fact that the wind blows in the hole and the wall vent restricts the flow thus compressing the air and driving the air down around the gap between the PB and the wall. There i s no such pressure build up in the roof space.

3: Fire retardant foam will not meet the fire resistance time requirements: they are petrochemical based and AFAIR, have a top temp resistance of 160C and thats for the expensive stuff used on planes.


I'm done here, keep well and good luck

ZV Yoda

Calahonda52 wrote: »

1 & 2: I would suggest you ease off a little on the tone here, we are trying to help you here so read MtM's post in its entirety and don't bridle at the suggestions:) Nothing is obvious here:)

2: I believe the wall vents are a bigger problem than the top of the PB due to the fact that the wind blows in the hole and the wall vent restricts the flow thus compressing the air and driving the air down around the gap between the PB and the wall. There i s no such pressure build up in the roof space.

3: Fire retardant foam will not meet the fire resistance time requirements: they are petrochemical based and AFAIR, have a top temp resistance of 160C and thats for the expensive stuff used on planes.


I'm done here, keep well and good luck

1. I can assure you, there's no tone intended. I haven't bridled (whatever that means!) at anything. I wouldn't be on a public forum asking for advice if I already had all the answers. That said, if I dont understand a comment or suggestion, I will ask for clarification. Hence the question about MtM's response. It's at odds with what the surveyor and engineer told me, so of course I'd like to get a better understanding. I'm learning as I go.

2. It is obvious air is swooping down behind the plasterboard - because I've been under the eaves & felt the wind coming in (it's an exposed SW facing rear wall). The thermal survey also showed this very clearly - lots of cold air circulating at the top of the walls, but less so in the lower sections. This what prompted the surveyor to investigate the attic in the first place. That's not to suggest it's the only issue. I've already said I'll be tackling the wall vents too (thanks to your suggestion). Likewise, I've already been sealing around windows & doors.

3. I've no idea about this & will need to investigate further. I was assuming this is the type of foam I'd need.

Thanks to the various posters for advice so far. If anybody else would like to chip in, I'm all ears.

mp31

Very interesting stuff... please can you PM me the contact details of the surveyor. Thanks in advance.

ZV Yoda

mp31 wrote: »

Very interesting stuff... please can you PM me the contact details of the surveyor. Thanks in advance.

PM sent

ct5amr2ig1nfhp

Can I jump with a question regarding the air vents? Calahonda52 mentioned to check the air vents. And after having a look at Yoda's, I checked my own vents. They are square type - on the external wall and on the internal wall. After checking all of our vents, none have any piping or conduit between the external wall and internal wall. I think this could be why I can feel a draught through most of our window frames, electrical sockets etc. The cold air/breeze is obviously flowing between the cavity.

I had a look in a couple of hardware stores today and I couldn't see anything that I could easily use to feed the air from external to internal wall. All of the piping was circular.

Is there an easy enough solution that would work for the square type vent? I'll try get a picture later.

ZV Yoda

Kairi Old-fashioned Underarm wrote: »

Can I jump with a question regarding the air vents? Calahonda52 mentioned to check the air vents. And after having a look at Yoda's, I checked my own vents. They are square type - on the external wall and on the internal wall. After checking all of our vents, none have any piping or conduit between the external wall and internal wall. I think this could be why I can feel a draught through most of our window frames, electrical sockets etc. The cold air/breeze is obviously flowing between the cavity.

I had a look in a couple of hardware stores today and I couldn't see anything that I could easily use to feed the air from external to internal wall. All of the piping was circular.

Is there an easy enough solution that would work for the square type vent? I'll try get a picture later.

Here's what I did... I bought some 4" waste pipe & expanding foam. I filled the wall cavities with expanding foam (to seal up the internal gaps where there was no insulation). Then I notched out the rough edges of the blockwork / foam so I could fit the 4" pipe snugly through the wall opening. Then I cut it to size.

After that, it was just a case of sealing the internal / external openings with a small bit of silicone around the pipe (probably overkill). Now, the air goes straight through the pipe & not into the wall.

This photo shows what I did. It's the outlet for the tumble drier (before I re-fitted the external vent). You can see the flexi pipe from the tumble dryer is sitting inside the pipe.