Thermal Lining + Sealing

mise_mise

Hi... I'm new to the site, I've found helpful so far... New Build, 2500ft. I would like to hear what you think in relation to thermal lining. Having attended the Home Expo in Letterkenny at the weekend, Duncan Stewart spoke about applying the insulation first, sealing in at all joints which aluminium tape and then covering them with plaster boards. He mentioned that this completely sealed the house to vapour. I had planned to use the thermal linear which has both attached as one board and sealing them with normal plastering tape. Any suggestions on how to approach this? I know i'm doing twice the work, but if its the best way to do so I don't mind taking my time to get it right!

justflow1983

mise_mise wrote: »

Hi... I'm new to the site, I've found helpful so far... New Build, 2500ft. I would like to hear what you think in relation to thermal lining. Having attended the Home Expo in Letterkenny at the weekend, Duncan Stewart spoke about applying the insulation first, sealing in at all joints which aluminium tape and then covering them with plaster boards. He mentioned that this completely sealed the house to vapour. I had planned to use the thermal linear which has both attached as one board and sealing them with normal plastering tape. Any suggestions on how to approach this? I know i'm doing twice the work, but if its the best way to do so I don't mind taking my time to get it right!

I think you need to do more research. Or talk to a construction professional. What you are describing is a technique used to insulate an existing building by dry-lining the walls and vapour sealing them. It may not be the best approach to a new build, and I think you should do a quick look around these forums as well as engage the services of an architect or architectural technician/technologist. Self-design is for those with a strong grasp of building physics.

mise_mise

Thanks for that. He was jumping from new build to old build in the presentation. I'll do some more research on it...

Mellor

justflow1983 wrote: »

I think you need to do more research. Or talk to a construction professional. What you are describing is a technique used to insulate an existing building by dry-lining the walls and vapour sealing them. It may not be the best approach to a new build, and I think you should do a quick look around these forums as well as engage the services of an architect or architectural technician/technologist. Self-design is for those with a strong grasp of building physics.

This isn't true.
While is is the method often used for existing buildings (due to the ease of retrofitting), it is also a suitable method for new buildings. There is no reason that a new build can't be internally insulated as long as it is detailed correctly (it works better for single story due to less tricky junctions). One con is the lack of "solid" walls for fittings.

Still contact a professional though. Architect or Architectural technician.

justflow1983

No bother. While I've mentioned it enough to make plenty of people sick, I'd suggest looking into a timber frame house if you're doing a new build. They're fast to build and a very robust and adaptable construction system. It also has a great deal of very current information about it bouncing around, which is the real reason i recommend it so much. A great US based information source is http://www.buildingscience.com/index_html and the irish equivalent is woodspec.ie

If you're looking into a block-built house, then homebond has a lot of the information you'll want to learn! Keep in mind that there are a lot of new ways of doing things because of the new energy regs.

justflow1983

Mellor wrote: »

This isn't true.
While is is the method often used for existing buildings (due to the ease of retrofitting), it is also a suitable method for new buildings. There is no reason that a new build can't be internally insulated as long as it is detailed correctly (it works better for single story due to less tricky junctions). One con is the lack of "solid" walls for fittings.

Still contact a professional though. Architect or Architectural technician.

I wrote "may not" as a qualifier, some people may still detail it on new builds. I'm not a fan on that technique in general, but would consider it on a refurb with an exterior that is to be retained. My reason is that it keeps your thermal mass on the outside of the insulated envelope while risking condensation at the insulation/block junction.

Mellor

Your two post above are very contradictory.

You recommend a timber framed building. Which would falling a similar category to internal insulation and vapour sealing (or breathing dependant). But then you say you are not found of internal insulation systems. Also, nobody mention block walls, concrete builds or themal mass.

mise_mise

mellor, thanks for the reply. I'm hoping to do this method myself, I intend on taking my time with it to ensure that it is sealed up properly. Would I need to attach the plasterboard to the insulation with anything else except the plugs, to ensure that I don't get moisture between the board and the insulation?

justflow1983

mise mise: From your post, I am assuming you are interested in building your house from block construction. Normally, I would recommend that the insulation go on the outside in order to avoid interstitial condensation in the assembly. Wherever warm air meets cold surfaces you can get condensation, and while theoretically your vapour seal would stop interior mosture migrating into the wall, there will still be some wetness in there that could condense between warm insulation and cold block on cold days. There is a short, and somewhat obnoxiously written, piece describing how your insulation should always be to the outside here: http://www.buildingscience.com/documents/insights/bsi-028-energy-flow-across-enclosures.

In Ireland, blockwork cavity walls are the typical form of residential construction. A blockwork internal wall is insulated to the outside of it with a certain amount of rigid polyiso/polyethylene or semi rigid rockwool insulation A 50mm air gap is to the outside of this, and then another block wall is put up which acts as a rain barrier and is rendered. The internal one is insulated to the outside and that way pushes potential condensation out into the cavity, where its ventilated and can dry without causing problems. You can omit the outer layer of block with some proprietary insulated renders or claddings. If you do the system you described with the internal linings, you'd still need the second leaf of block as a rainscreen.

Mellor, I kept my answers short because I wanted to let the OP do their own research rather than latch onto the first system they saw from Duncan Stewart. Nobody mentioned block walls, but I don't see why you would internally line any other type of construction so I assumed that was the type of build.

In a timber frame building you are not internally insulating the building, especially if you don't put up a block outer leaf (which is a rainscreen anyway and performs very differently). The insulation is concurrent to the load bearing structure, and even then you should further wrap the timber frame with a continuous layer of external rigid insulation in order to pull the dew point (condensation temp) out of the structure and into something inert. In TF you put a vapour control layer, which should be reversible in some conditions, to the innermost side of the timber frame to keep interior moisture from getting into the structure and causing mold growth. You then make the entire assembly vapour permeable to the outside so that moisture can migrate out and keep the structure dry. Again, very different from the system described by the OP in performance where moisture can get trapped between the vapour seal and blockwork which doesn't allow moisture to migrate well.

If you put block to the outside of the timber assembly, it is always on the outside of a ventilated air space which means that the timber frame is essentially the outer thermal layer. The block becomes a rainscreen, and the gap reduces the damage of interstitial condensation to the back of the block by keeping it off the timber, although I would advise against this type of construction because you are producing a damp microclimate against timber frame which is a hygroscopic material. Again, a very different thermal behavior than internal drylining.

Mellor, don't try to catch people out like that, it turns out they may actually have real reasons for their advice. Plus, these things require a lot more nuance than you seem to give credit for.

Mellor

Mellor, I kept my answers short because I wanted to let the OP do their own research rather than latch onto the first system they saw from Duncan Stewart. Nobody mentioned block walls, but I don't see why you would internally line any other type of construction so I assumed that was the type of build.

I kept my answers short for the same reason.

And I never suggested that internal lining was the best way to go. Nor didn't I even suggest the OP use that method. I said to consult a professional. I was mostly refering to vapouring sealing with is a huge part of modern dwelling design due to the benefit of HRV.


You don't see why you would internally line any other building? Really.

How about a timber building, where the sought insulation thickness is greater than the required stud thickness. Oversizing the stud is poor detailing its much better to cross and line with more insulation. This also serves to eliminate a huge portion of cold bridges.
(I do agree that externally is best, but internally is also an option and better than not at all)

If you put block to the outside of the timber assembly, it is always on the outside of a ventilated air space which means that the timber frame is essentially the outer thermal layer. The block becomes a rainscreen, and the gap reduces the damage of interstitial condensation to the back of the block by keeping it off the timber, although I would advise against this type of construction because you are producing a damp microclimate against timber frame which is a hygroscopic material. Again, a very different thermal behavior than internal drylining.

Hygoscopic? Are you sure this is what you meant to say.

Mellor, don't try to catch people out like that, it turns out they may actually have real reasons for their advice. Plus, these things require a lot more nuance than you seem to give credit for.

I just pointed out that your post wasn't accurate. It wasn't, get over it.
I never tried to catch you out. You are the one that have gone off-topic. I suggest you lose the attitude, as there are better ways to post advice (which so far has been good)


OP, I refer to the my post. Get professional advice. Depending on your build type, there are different options for insulation

justflow1983

I'm bad about leaving these things unresponded to.

Mellor wrote: »

And I never suggested that internal lining was the best way to go.

If somebody asks about something unsuitable, you should let them know otherwise.

Mellor wrote: »

You don't see why you would internally line any other building? Really.

Nope, its bad practice. Maybe if I wanted a stone facade.

Mellor wrote: »

How about a timber building, where the sought insulation thickness is greater than the required stud thickness. Oversizing the stud is poor detailing its much better to cross and line with more insulation. This also serves to eliminate a huge portion of cold bridges.
(I do agree that externally is best, but internally is also an option and better than not at all)

Internally is a good way to have mould growth in timber frame, so again, bad practice that shouldn't be suggested online to non-pros. Plus, in a new build its pointless to do things wrong.

Mellor wrote: »

Hygoscopic? Are you sure this is what you meant to say.

Google it. No architectural professional should not know that word.

Mellor wrote: »

I just pointed out that your post wasn't accurate. It wasn't, get over it.
I never tried to catch you out. You are the one that have gone off-topic. I suggest you lose the attitude, as there are better ways to post advice (which so far has been good)


OP, I refer to the my post. Get professional advice. Depending on your build type, there are different options for insulation

It was neither accurate nor inaccurate. If you look at my initial post it was a lot more open than you seem to be able to read.

mise_mise

Thanks again to you both. Very informative. As I said, new to the site. Lack of information given at the start so here it goes again.

2500ft hosue, 1 1/2 story
oil burner
23 rads

Floor had 50mm kingspan boards
310mm Cavity walls have 60mm quinntherm cavity sheets and a 50mm cavity. I'm nearly sure of putting the 50mm insulation with 12.5mm plasterboard on the inside leaf.
Roof will have 150mm rockwool with 12.5mm plaster boards sealing that area of the attic.

Upstairs ceilings to have the same spec as the walls with 200mm rockwool in the ceiling joists.

Thanks again to you both, your disagreement came from my lack of information... sorry!!!!

sinnerboy

Rule of thumb - keep the drylining down to max 1/2 the thickness of the cavity insulation . Otherwise you risk trapping interstitial condensation in your inner leaf Personally I would not choose cavity wall or dry lining and would look to in no particular order

1. Rendered external insulation on solid blockwork (200 ins , 215 block )
2. Closed panel timber frame ( 200 stud , cellulose filled , 75 ~ 100 wood fibre board to external , intellegent VCL and 50 insulated services cavity . If you preplan the electrics - have the conduits factory fitted
3. ICF .

You will need at least 120mm floor insulation and 300mm Rockwool roof insulation

You will need some renewable energy installations ( solar / wood pellet/ Heat Pump )

But more than anything else you need to hire expert help - not only to prepare the spec but to see it implemented on site .

Mellor

Mellor wrote: »

Hygoscopic? Are you sure this is what you meant to say.

Google it. No architectural professional should not know that word.

I am well aware what hygroscopic means. The reasons I asked was it's a fairly obvious property of timber and insulation. Appeared a bit pedantic to state it. And also because it's often used as a positive property in relation to building materials (Such as sheeps wool's hygroscopic proformance) so it's use would do nothing other than confus a layperson.



I don't know what you have such a chip on your shoulder? For the second and last time lose the attitude, it helps nobody.

The OP has posted details on her specific build that show that lining is unsuitable. (OP, in a new build, there is no point separating the insulation like that). Again, I never suggested to her to use that method as that would be foolish with on other info other than New Build, 2500ft. I was disagreeing with your post that said lining is unsuitable for new builds. (I agree in terms of cavity construction) But there are other build types that are suited to it. Paticularly were external finish is concerned, or where the dwelling isn't a block build.

justflow1983

I would agree with Sinnerboy's post as to what construction types you should look into. Those 3 types are what would currently be considered best practice in residential construction today. I wouldn't use 1 or 3 in my own work, but that is a values judgment to do with the fact that they are high in embodied energy and their manufacture isn't very environmentally friendly. Still, they are effective, proven, and reliable. All three should be looked at as the basis for your new build, and are used widely so there is plenty of information about them available on the web.

I don't really have a chip on my shoulder, I just felt that picking so directly what I initially wrote, broad as it was, was petty. It helped neither the OP nor the discussion, and was based on unsound principles. I come from a family of lawyers and get sucked into arguments very easily. I'm a stubborn pain in the butt in real life too; it serves me pretty well actually.

OP: Hygroscopic properties are good to have, but they are something one needs to be careful about. In a situation where the materials are allowed to dry frequently, then being hygroscopic is a good thing because it reduces ambient water vapor in the assembly by embedding it in the material. However, if the construction used is not vapor-open, then the moisture stays in the materials and you get fungal growth. A lot of my opinions on this kind of thing are from reading papers by Joseph Lstiburek, who has done extensive research on timber frame and moisture. Niall Crosson on this side of the atlantic has also published invaluable information on it, and is probably a better source regarding breathability.

I'm primarily a designer, but I read extensively on the technical side to make sure I don't do anything stupid when it comes to my client's buildings. That means only working with best practice methods and not halfway measures, and I stick to that philosophy here because I don't want to take the risk of a poster getting the wrong idea and having trouble with their home further down the line.

Mellor

justflow1983 wrote: »

I don't really have a chip on my shoulder, I just felt that picking so directly what I initially wrote, broad as it was, was petty. It helped neither the OP nor the discussion, and was based on unsound principles. I come from a family of lawyers and get sucked into arguments very easily. I'm a stubborn pain in the butt in real life too; it serves me pretty well actually.

Apologies if I came across as petty. Generally, if something may get taken up the wrong way, or leave out a small area it'll be corrected. While this can result in a lot of pedantic "corrections", it's something we live with as it probably best for the OP, who are normally laypeople.

Anyway, welcome to the forum