Facade board 30 mm - Frame and get thermal bridges, or not?

[Turinna]

Hello everyone!

I am planning to add extra insulation to my house before installing a new wooden facade. The house has a timber frame, and I'm caught between my contractor's and Isover's building recommendations...
Now, Isover's technical support is on holiday and I need to make a decision.
Help!!

1.
Isover claims that you should not use studs but install the facade boards edge to edge to avoid thermal bridges, then nail battens - at least 22x70 - on the corresponding spacers inserted in the joints and one in the middle of the board, and then nail the facade on the battens.
(With Isover's method, you get a ventilation gap of 22mm behind the facade)

2.
My builder claims he needs to use 34x45 studs to even out the timber frame, install the boards between the studs, and then nail the facade onto them.
(With the builder's method, you also only get a 4mm ventilation gap behind the facade).

The timber frame is probably not perfectly straight, but not very uneven either.

Is what the builder says correct?
Or is there a way to even out with the spacers that should be used (Isover did not advise against their method even though I mentioned we have a timber frame), does it seem strange to you that Isover's method couldn't be used on a house with a timber frame, don't you think??!

Can you advise me??

 

[EddieHansson]

If you have vertical siding:
Panel
Horizontal 22x45 (air gap)
Windproof paper/membrane
Horizontal 45x45 (fill with insulation). Offset in relation to the innermost layer horizontal.
Vertical 45x45 (fill with insulation)
Horizontal 45x45 (fill with insulation)
Existing wooden wall

You can adjust 45x45 according to how much insulation you need. Change the order if you want horizontal siding.

 

[Turinna]

Thanks, but did you see what the question was?

Studs or no studs for mounting the 30 mm facade board, that was the question:
-Isover says no studs (to avoid thermal bridges)
-The builder says studs (because he needs to even out the log frame)

 

[Jan_G]

Facade panel = not studs. Follow the manufacturer's instructions. Then they will be responsible for any future issues.

 

[bossespecial]

Since the timber frame is not straight, listen to the builder who will be responsible for the final result. Installing the boards on an uneven frame will only result in uneven joints and thermal bridges, as well as a lot of irritation when the facade is put up.

 

[EddieHansson]

Thanks, but did you see what the question was?

Studs or no studs to mount the facade board of 30 mm, was the question:
-Isovel says no studs (to avoid thermal bridges)
-The builder says studs (to even out the timber frame)

Yes, but I may have been unclear. The facade boards are not much better than regular insulation, but often more expensive and require a good fit to work. If you offset the studs, the thermal bridge will be minimal.

You need it reasonably straight to get a nice finish with the facade boards later, so from that standpoint, I also think the builder's suggestion seems better, but that you add a 22x45 for a better air gap. 4mm is sufficient. Worth installing a mouse mesh for the air gap.

 

[Turinna]

Thank you, Eddie!
But you mean that 4mm is NOT enough (although you wrote that 4mm is enough) and that I should therefore add a 22x45?[/QUOTE]

 

[Turinna]

Since the timber frame is not straight, listen to the builder responsible for the final result. Installing the boards on an uneven frame will only result in uneven joints and thermal bridges, along with a lot of irritation when the facade is installed.

Thanks!!

 

[Turinna]

Fasadskiva = not studs. Do as the manufacturer says. Then they will be responsible for any problems in the future.

That's how you'd want to do it! BUT I'm unsure if there's a solution to the problem with the uneven timber frame, as Isover's spacers aren't adjustable as far as I know, and you certainly don't want to have a warped facade...

 

[useless]

The basic problem, as mentioned, is that the structure is uneven. The best solution is what the builder suggests, which is to first level it out and then insulate. If you insulate between the studs, no rigid facade boards are needed, and it works with regular boards and wind protection fabric. Then you add another layer of studs with nail battens before putting the facade so you get an air gap.

 

[Turinna]

If you have vertical panel:
Panel
Horizontal 22x45 (air gap)
Windpaper/membrane
Horizontal 45x45 (fill with insulation). Offset relative to the innermost horizontal layer.
Vertical 45x45 (fill with insulation)
Horizontal 45x45 (fill with insulation)
Existing wooden wall

You can adjust 45x45 based on how much insulation you need. Change the order if you want horizontal panel.

In this house, I can't use regular insulation and especially not 2 layers of 45mm, because then we would have to extend the roof overhang, and that would be too expensive a story...
So therefore, it will be in order: wind membrane, a 30mm façade board between studs with the smallest possible air gap because we want to minimize how much the wall builds (the builder had planned for 4mm with a 34x45 stud which sounds too little, as I said, but I'm unsure of how little is the minimum?) and façade on that.

 

[Turinna]

The core problem, as mentioned, is that the frame is uneven. The best solution is what the builder suggests, that is to set up a straight structure first and then insulate.
If you insulate between the studs, no rigid facade boards are needed; ordinary boards and a windproof membrane will suffice. Then another set of studs is attached with nail battens before installing the facade to create an air gap.

I think facade boards were chosen to achieve the most effect with the smallest possible thickness (because we want to avoid extending the roof overhang). So ordinary boards, what do you mean by that? Are you referring to regular loose-fill insulation boards?
And how much air gap do you consider the minimum?

 

[useless]

So regular panels, what do you mean by that? Do you mean regular loose wool panels?

I mean regular mineral wool panels sold in all hardware stores. Loose wool is not panels...

The biggest advantages of façade panels are that they are rigid and windproof, but if you still have to use studs and put windbreak fabric on top, you don't benefit from those advantages, and it just becomes a more expensive product.

 

[Turinna]

I mean regular mineral wool boards that are sold in all building supply stores. Loose wool is not boards...

The biggest advantages of facade boards are that they are rigid and windproof, but if you still have to batten and put windproof fabric on the outside, then you won't benefit from those advantages, and it will just be a more expensive product.

and regular mineral wool boards (excuse an ignorant one) are available in 30 mm and are just as effective?

 

[useless]

The minimum standard dimension is 45 mm. But spontaneously, 30 mm of additional insulation feels very little when considering potential savings in relation to the investment, but if that's all that fits, there might not be much to do.

However, I don't think it's a problem to fit a 45 mm board if you install it outside the uneven frame. The advantage of "regular" boards is that they are much softer, so you can compress them a bit, and they adapt to the surface. Hard facade boards will create an unwanted air gap between the board and the timber frame where cold air can find its way in.