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Restoration & Refurbishment Question
Firewall construction material and thickness
We are converting an old corner shop and the living accommodation next door and above into two individual houses. Pre-planning advice was positive and we are awaiting formal approval. Unfortunately the current party wall is only one single brick thick i.e. 4 inches plus plaster on both sides. As we are speaking to builders we are receiving conflicting information about the need for a more robust party wall/firewall. The advice ranges from (1). Digging 1m footings and building an insulated cavity block wall finished with dab and 12.5mm plaster boards plus a skim (2). Building an insulated 3 inch timber frame and dryline with 12.5mm boards plus skim (3). Fix fireproof 12.5mm fermacell board with special fittings and skim.
Would a fireproof board plus skim to one side of the wall and soundproof plasterboard plus skim to the other side be a viable solution? .
The total area to be covered including the loft/attic space is 60sqm per each side of the wall
Which solution would you recommend?
Thank you in advance for your advise.
This is a common question and in fact is very simple. The work you are doing needs building control approval. So you need plans prepared for the approval of building control. The surveyor who prepares the plans will measure the thickness of the wall, plaster, all relavent factors and will prepare plans on this basis, detailing what is needed on the wall. Assuming building control approve it, then as long as you copy the plans, that is all you need to do.
There are two bits of advice though. Use a competant surveyor to do the plans, some are a bit thick. We use a building inspector to do our plans, so he never gets it wrong. The second is use a competant builder, most are a bit thick and will try to cut corners. Then, when the building inspector turns up to check the work is according to the plans, if it is not, it will all have to be taken down and done again. Building Inspectors have the absolute power of yes or no, and as long as the builder follows the plans, there is never a problem.
Answered 10th Jan 2012
Building Control is the first stop. However suggesting several options to suit your requirments will be taken into consideration and any good builder will sugest solutions.
Tanalized 1"1/2 battens screwed to the existing wall with 2x fire line 12.5 mm
gypsum board first layed horizontally the next screwed' vertically will give you an hour's fire saftey.Infill the batten with 50mm rockwool and you increase the fire rating and get better sound insulation. (only infill if the party wall is above ground and totally dry) Morturn Associates Ltd.
Answered 11th Jan 2012