Dry Lining a Lean-to Carport! - Any Heads Up?

[n-hatton]

Hi All.


Currently quoting a friend to "do up" their brick built lean-to. Looking for any "heads up" or advice before undertaking.

It's a non-cavity brick wall with damp proof course parallel to the external rendered wall of the house. Roof pretty much as per a car port; timber frame fixed to house wall and sitting on wall plate on non-cavity wall then covered in corrugated sheet - the black opaque stuff. Been assured all's water tight and dry; which it appears to be.

They understand it can't be habitable, just want it to look like a utility room off the kitchen.

Am proposing pre-constructed timber frames that I then fix to all existing walls. In-fill with glass fibre insulation. Then plasterboard all. Advised them against plaster boarding the roof - suspect joints will just keep opening up with typical movement from a car port roof. Tongue and grove softwood now required.

Anyone see any issues?

What about non cavity wall; any moisture issues that I may need to consider?



Cheers,
Neil

 

[noseall]

It is doable but it smacks of silk purse out of a sows' ear.

There will always be issues of damp and condensation that will crop up, of which it will be you they will look at for answers.

I would ask them to seriously consider something more robust, from scratch. Otherwise how do you tell them that they are going to spend a heap of cash on something that will throw up problems later on.

 

[n-hatton]

Noseall.


Yes, I realise it's a silk purse out of a sows ear - that's exactly what the customer is asking for. They've turned down a number of proper builders quotes to do a proper extension as all's well out of budget.

Have done stuff like this internally no issue; not quite like this though and interested to know of such issues.

Is there any moisture backed plaster board, or a form of membrane I can place over timberwork before boarding out etc?

 

[PrenticeBoyofDerry]

Is there any moisture backed plaster board, or a form of membrane I can place over timberwork before boarding out etc?

Yes
duplex foil backed boards, the foil is used as vapour check barrier, or you can install a vapour barrier yourself and board over.

http://www.british-gypsum.com/produ.../gyproc_standard/gyproc_wallboard_duplex.aspx

http://www.screwfix.com/search.do?f...=P&gclid=CJTv0vjB6qACFQ6Y2AodUjfcdQ&source=aw

 

[n-hatton]

Prenticeboy,


Nice one Found some info via Google search and B&Q website - though Screwfix links you sent much better.

Assume I can't go overboard by using the heavier floor based membrane sheet against the walls 1st, then my timber battens over the top of that, then final vapour barrier+ conventional plasterboard (or alternative all-in one vapour board)?

Assume need to also protect the timber, and by having membrane either side of it won't cause ventilation issues to timber?


Cheers

 

[PrenticeBoyofDerry]

If you look at this link
http://www.insulation.kingspan.com/uk/pdf/k18.pdf
It will give you some useful info on what's best to do.
It does show using thermaline boards, which will add to your insulation values, but you could get away with an insulation infill within the stud work and then apply either duplex boards or standard 12mm boards and a vapour barrier, the thermaline boards also have a vapour check.

 

[ajrobb]

Just a few thoughts:

Being a utility room/garage and no indication of damp proofing on floor, would a more robust, moisture resistant board like Duraline MR be appropriate? It doesn't have a VPL so you'd need a membrane if your going to insulate.

Proctor group's Reflective Technology brochure shows a timber frame lining. They show a 50mm cavity (galvanised steel spacers/ties?) lined with either their Frameshield or Reflectashield permeable membrane then OSB with 89mm (115mm for Scotland) studs with mineral wool infill. This is covered with a VPL and finally plasterboard. However, it looks more like a brick cladding on a timber frame building and probably overkill.

An insulation option might be Crown Dritherm slabs. These are designed to be used directly against the outer brick layer as they are treated with silicone to prevent penetrating damp problems. They have a slightly lower conductivity of 0.032 rather then 0.04 for a 'typical' mineral wool (so you only need 80% of the thickness).

If you fix the battens to the brick wall, you might consider treated timber.