Underfloor ventilation for new extension

[DougieBrown]

In order to ensure through air flow from the front of the house to the back the guy drawing the plans for a ground floor side return extension has suggested excavating a 700mm void under the entire new floor area, laying a concrete base with joists running above the void. The builders have suggested a solid screed onto the ground with ventiation pipes running through. The latter is a lot cheaper as does not involve excavating the entire floor area.

Thoughts on why either may be more appropriate would be appreciated.

Thanks

 

[oldbutnotdead]

So what you're being offered is solid floor vs suspended floor?

For me it comes down to what type of floor you like- ventilating existing space will work via (min 110 diameter) pipes under your slab or by through ventilation from the new suspended floor.

Either way I'd put a couple of extra air bricks/holes in the existing walls first to increase airflow.

I prefer suspended timber floors to solid concrete- gives you more freedom to change or add things in the room later. But that's just me- from a construction point of view solid concrete screed is quicker and cheaper to put down (no real carpentry skills involved and fewer sheets of insulation to cut so less waste there), if you're going to carpet the job and have got all power and pipework taken care of then crack on. either scheme will work (though the screed option might get more expensive if the ground it is going onto is soft).

 

[freddiemercurystwin]

Ground bearing floors every time unless there's some major reason as to why they're inappropriate. Separate pipe ducts to vent an existing suspended floor is the way to go, have a look here: //www.diynot.com/forums/viewtopic.php?t=171482