Cladding options - Cedral weatherboard or Freefoam?

[TonyS82]

Hi all,

I need to replaced the 35 year old (rotten in places) timber cladding on my timber frame mid terraced property, which covers half the front of the house and the entire rear fascade but am at a loss as to which option would be best.

I had wanted to remove the timber cladding completely back to the plywood board, add new insulation, new batons, new membrane and install cedral weatherboard.

I thought adding the insulation made sense whilst the cladding was off, but one company said adding insulation may create issues with moisture/damp in the walls. He said that in his opinion it would be better to clad over the existing timber with a product called freefoam fortex.

I am now at a loss as to what would be best.

Does anyone here have any experience with these products that can offer any advice? Obviously not having to remove the timber cladding would be a hefty cost saving, but in all honesty I would rather get the right job done,even it is the more expensive option.

Here is an old picture of the front of my property if it helps

Thanks

 

[tomfe]

I would do as you first said. You are also required by regs to improve the insulation if you are replacing that much cladding.
Make sure you have a vented void between your cladding and insulation.
Make sure your roof overhangs the new cladding.
With cladding the junctions and detailing are the most important make sure you have some drawings etc of these, you can get them free off the internet.

If you don't remove the existing cladding you won't beable to get the new insulation tight against the building so you might get problem with damp, it would also allow you to evaluate any other repairs needed.

From that picture your cladding does not look too bad maybe sell it on or reuse it to make a shed etc.

I've used that cement cladding before it's a good product, I would not go with a vinyl foam product.

 

[TonyS82]

Thanks Tom

Out of interest, any particular reason you wouldn't use the vinyl products? I was told it the finish is better, longer lasting and easier to clean.

I have also seen some cement cladding locally where the joint between two lengths are not sitting flush. Is this more of a installation issue?

I wouldn't be doing this myself, is there anything I should the job is be asking when it comes to getting quotes to make sure the job is being done properly?

Here is the rear of my house, as you can see it would be quite a big job. It is rotten all across the bottom.

 

[catlad]

I would stay well clear of the guy who wants to overclad you old timber!
stripping it back to its structural timber and insulating is the way forward.
I have used the weatherplank cement board and its much
better than plastic cladding.

 

[tomfe]

Just personal preference really but I don't like all the trims and joints and the feel, I am sure the fire rating is good but something in my head seems to think it's a bit of a risk.

 

[TonyS82]

Thanks gents,
Do either of you think I should be concerned about the moisture/damp issues if adding insulation?

 

[chappers]

agree with the others, strip back insulate nice and tight and batten over. the cedral stuff is brilliant and the guy you spoke to doesn't know what he is talking about the cedral stuff won't rot and should last for ever.
You may have already looked on the cedral site, the installation pages show all the detailing around windows etc and the relevant profiles.
I have fitted it both with homemade profiles and the proper profiles and whilst either works well the commercial profiles are definitely better.
It isn't cheap mind, especially if you go for the pre-coloured stuff, but I have also fitted the raw stuff too and it paints up really well too. It kills saw blades though and they recommend diamond tipped blades, but when I have used it I have just brought cheap blades and treated them as disposable

 

[TonyS82]

Thanks gents.

Any recommendations on membranes and ventilation gap width if I use 25mm or 30mm eco-versal.

Thanks

 

[catlad]

I can't see you needing anymore than an inch gap in your scenario.
Membrane l would chose a light weight one.

 

[TonyS82]

So I have settled on the cement weatherboard and we are probably going with ecotherm eco-versal 25mm insulation. (I live 5 minutes from their factory and they have been helpful with condensation risk and u value calculations).

I took a piece of plaster board out and measured what was there so this will be the wall construction internal to external:

12 mm foil backed plaster board
90mm studwork (currently filled with approx 20 to 30mm of wool insulation).
10mm ply sheathing
25mm eco-versal
Membrane
25mm timber battens
Cement weatherboard

How does this sound? I know it won't necessarily meet current building requirements for insulation but it's an improvement over what's there currently.

Thanks for all your help.

 

[tomfe]

Can you full fill your studwork cavity, if not then your 20-30mm insulation will need to be pushed back against the sheathing ply.

 

[TonyS82]

Tom
Unfortunately unless we take the ply down I can't fill the cavity.
We are planning to install the insulation directly on the ply sheathing, then membrane, new battens and then the cladding.

 

[TonyS82]

Sorry gents, one more question.

Should the membrane be installed directly to the exterior side of the new insulation and then the battens and cladding over that? Or should there be a air gap between the membrane and insulation and then a ventilation gap before cladding.

It's seems there are contradicting answers on the Web.

 

[chappers]

yep membrane, battens then cladding

 

[catlad]

You should be insulating between the studwork leaving an inch gap so when you fit the membrane on the studwork you will have an inch gap behind, then fit you batons to the studwork which will give you another gap behind the cladding.