Sub floor options

Moggaman

Hi .
My contractor is filling between rising walls next week before a sub floor pour. The blocklayer has left the internal walls down a block to suit radon installation. My engineer he given 2 options with regard to the last internal block..1. Blocklayer to come back and lay one course over radon prior to poring.2. Leave internal course down and pour subfloor straight through over blocks
Just wondering what is the advantage of both..
I understand that with option 2 , some wall load with be spread to the floor ?
Thanks

sydthebeat

I usually try to encourage option 2.

screeding the whole area after is harder (though you dont have to be perfect as its a subfloor), but the risk of floors slipping is greatly reduced.

just make sure you dont change the location of walls after the subfloor is poured.

Moggaman

sydthebeat wrote: »

I usually try to encourage option 2.

screeding the whole area after is harder (though you dont have to be perfect as its a subfloor), but the risk of floors slipping is greatly reduced.

just make sure you dont change the location of walls after the subfloor is poured.

Thanks Syd... does option one mean a lot more airtightness tape before finished floor level pour ie each wall floor junction .. shouldn’t be much of a cost just a bit of time?... thanks

sydthebeat

Moggaman wrote: »

Thanks Syd... does option one mean a lot more airtightness tape before finished floor level pour ie each wall floor junction .. shouldn’t be much of a cost just a bit of time?... thanks

really depends on your build type and your target air tightness.

i wouldn't even consider air tightness tape for a masonry build with a target air tightness of around 2.0... id just insist that the plaster plaster down to the floor level, and the skirting board be properly caulk sealed.

Moggaman

sydthebeat wrote: »

really depends on your build type and your target air tightness.

i wouldn't even consider air tightness tape for a masonry build with a target air tightness of around 2.0... id just insist that the plaster plaster down to the floor level, and the skirting board be properly caulk sealed.

May sound odd but my target is the best I can reasonably do without going mad.. I will tape around windows and had intended on taping the floor . the tape has to lap the wall airtightness layer which is the plaster? . so I will tape from finished screed up the block wall prior to plastering?
Thanks

sydthebeat

Moggaman wrote: »

May sound odd but my target is the best I can reasonably do without going mad.. I will tape around windows and had intended on taping the floor . the tape has to lap the wall airtightness layer which is the plaster? . so I will tape from finished screed up the block wall prior to plastering?
Thanks

are you planning on using a membrane on the uppermost ceiling?

are you planning on UFH in a screed after the plastering?

in my opinion taping from the screed onto the block wall is a waste of time when you can just insist that the plasterer plaster down to the screed (properly, not leave a bow)... or in the case of UFH, just insist the plastering is done before the finishing screed is poured, and pour slightly over the edge insulation level.

then after you fix your floor covering (hint, tiles adhesive here will also help the junction as well) you just make sure your skirting board is caulk sealed at the bottom and at the top

Moggaman

sydthebeat wrote: »

are you planning on using a membrane on the uppermost ceiling?

are you planning on UFH in a screed after the plastering?

in my opinion taping from the screed onto the block wall is a waste of time when you can just insist that the plasterer plaster down to the screed (properly, not leave a bow)... or in the case of UFH, just insist the plastering is done before the finishing screed is poured, and pour slightly over the edge insulation level.

then after you fix your floor covering (hint, tiles adhesive here will also help the junction as well) you just make sure your skirting board is caulk sealed at the bottom and at the top

Yes to a membrane on upper most ceiling - it will lap with wall plaster .
Yes to screed with UFH...

Thanks for your comments on plastering before finished screed.. that seems like a good plan..

I assumed the airtightness tape was a must..but there are obviously many ways to do it