Cavity Closers

[staningrimsby]

Ho guys,

Heres another quick one for you,

i am having a go at building a small extension, it will have an 85mm cavity and both internal and external leaves will be made form lightweight concrete blocks, wich will be rendered later.

My questions are do i need to use cavity closers were the opening is for the external french doors ??? and what exactly is insulated DPC as i have been told i will also need this in the opening ???

 

[mikric]

Insulated dpc is just normal dpc with a thin layer of polystyrene stuck to it.
Here in my area we cannot use this method any more ,and only insulated cavity closers are acceptable for building regs, so my guess would be go for the closers.

 

[chessspy]

Hi, It's been a few years since it was allowed to close the cavity with blocks, as this forms a temperature ramp at the reveal.
So now it's the plastic insulated cavity closers that are insisted upon, You buy em in 8ft lengths and cut to length.
If you haven't seen em, the look like plastic 4x2" with a lip on for nailing to the blocks. Use em for sealing across the cill also.
85mm sounds a bit wide for a cavity, normal is 65mm I think

 

[Shytalkz]

There are still block closing details that work under current regs; see the Thermalite site.

 

[chessspy]

Hi shytalks,
I suppose thermal block makers would want that, however it's lots quicker to let the labourer do it later.

 

[noseall]

it is still permissible to use a block return with dpc at window and door abutments, provided the blocks are aerated thermal fellas.

we never do as it is quicker to buy closers and tack 'em in later.

 

[staningrimsby]

Cheers for that guys, i guess i will have to look into the insulated DPC option to close the cavity as that is what the architect has specified in his drawings.

 

[chessspy]

God help you Stan,
The best thing to do with drawings is to use them to light the pyre under the Architect.

 

[staningrimsby]

Cheers Mate,

Yuor really inspiring me with confidence, ive already discovered today that the architect has mentioned electrics, lights radiators or site preperation (whatever that is) in his specification.

 

[chessspy]

Here is a handy guide to architect speak.
Electrics, = Electrician will do it right not to drawing, which is wrong.
Lights,= see above.
Radiators,= Get in a central heating firm to persuade you to replace a perfectly good boiler on the grounds that it is 6 months old, (can't get the parts, Might not be able to get the parts at some unspecified time in the future etc)
Site preparation, = Dig up turf before starting.

 

[freddiemercurystwin]

Here is a handy guide to architect speak.
Electrics, = Electrician will do it right not to drawing, which is wrong.
Lights,= see above.
Radiators,= Get in a central heating firm to persuade you to replace a perfectly good boiler on the grounds that it is 6 months old, (can't get the parts, Might not be able to get the parts at some unspecified time in the future etc)
Site preparation, = Dig up turf before starting.

You seem to have something against architects chessspy? For every useless architect you can find a useless builder. Horses for courses.

 

[noseall]

You seem to have something against architects chessspy? For every useless architect you can find a useless builder. Horses for courses.

 

[^woody^]

Cavitiy closures and insulated DPC are a con.

Pack the end of the cavity with insulation and gob it up with mortar

Or, just run a can of expanded foam around the cavities at the reveal.

 

[chessspy]

Thanks nose, nice one.
Oh come on woody someone might take you seriously, tut tut

 

[Delinquent]

God help you Stan,
The best thing to do with drawings is to use them to light the pyre under the Architect.

Exactly what I'm planning (excuse the pun) to do with mine. If I hadn't decided to modify the extension and re-do the drawings, we probably wouldn't have realised that the roof wouldn't fit on the architects version.

Still, only cost a couple of £k for a few sheets of A0 paper...