Floor Build up Questions

[padstar]

About to start the 2nd part of the extension which is the main rear build. The architect has drawn a typical slab laid on insulation. to the extension. I want the existing rear rooms that will form part of the larger new room to have the same floor construction.

I don't like the idea of slabs so started looking at Block and Beam flooring which would be ideal to run in the existing and new locations. The problem is that there is not enough depth from existing finished floor level less screed, insulation, block and beam and then to leave a 150mm void for air flow.

The question then came of why cant traditional suspended flooring be used? Obviously this would need to be insulated between the joists to current BR's. My BCO has allowed me to do this in teh smalle front extension.

Is there an issue with teh traditional method and why don't people use now days. Surely it is perfect for running services and any future alteration works?

 

[oldbutnotdead]

Trad suspended timber floors are still allowed, you still need 150 clearance below joists to oversite (dpm with concrete or gravel, its all in the ADs)
More labour intensive, more skilled work required, timber isn't cheap. But yes bonus is access to void for services

 

[padstar]

Thanks for the response. So the traditional method is still fine to use and has only become redundant due to cost reasons (and arguably better thermal insulation in slab construction methods?

Taking the costs out of the conversation are there any major disadvantages to using the traditional suspended floor method?

 

[oldbutnotdead]

Requirement for subfloor ventilation- need to detail your insulation to avoid draughts.
If you're in a flood prone area the airbricks let the water in, timber floors take a while to dry out & if you have chipboard down it'll be FUBAR .
Timber floor is noisier- foot noise and creaking if the boards aren't fixed down properly.
Think those are the main non-cost issues...oh yes, floor void is handy for rats and other vermin to live in

 

[padstar]

Thanks again. I think they are all manageable issues especially as the rest of the house is in this method of construction.

 

[^woody^]

Why would you want a bouncy rattly floor if you didn't need to?

 

[padstar]

I can forsee alterations to the services over the year after the floor construction. This would be very problomatic with a solid slab.

 

[oldbutnotdead]

I like trad timber floors (with the floorboards on show, not that much dearer than chipboard). If i did have a concrete floor i'd probably cast a trough in it for pipework & ducts for cabling.
The whole future changes bit- wouldn't worry about it for anything except data, your planned changes are unlikely to happen or if they do there'll be other ways round it. Island kitchen conversion would be about the worst...

 

[^woody^]

Plan ahead, form ducts.

 

[padstar]

Is it possible to have a service duct around the perimeter of the slab?

I must admit I am still not sold on the slab. As the existing GF is a suspended timber construction, why not just tie in in the same method?