Solid floors - membrane under OSB?

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eggerb

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I'm having solid solid wooden floors fitted onto a concrete floor in a new house. The moisture content seems to have fallen to an acceptable 3-5%. Exactly what type of membrane am I looking to put under the the OSB / on top of the concrete? Will the fitter supply this?

Thanks!
 
I would recommend a barrier of 1000 gauge polythene, you could use 500 gauge but it's very easy to damage such a thin membrane. Overlap all joints by 100- 150mm and seal the joints by tape. Use a duct tape for a top quality job- you can get a generic duct tape that's fairly cheap. Don't know about reducers though.
 
Carpenter said:
I would recommend a barrier of 1000 gauge polythene, you could use 500 gauge but it's very easy to damage such a thin membrane. Overlap all joints by 100- 150mm and seal the joints by tape. Use a duct tape for a top quality job- you can get a generic duct tape that's fairly cheap. Don't know about reducers though.
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Do these piercings increase the risk of moisture absorption by the OSB and boards. Is there any other way of fixing the OSB to the concrete without piercing the polythene?
 
"Anchor fixings"- he might be using express nails, which will certainly puncture the membrane and render it pretty useless IMHO. I had assumed that you were laying a floating floor but can I now guess that your chippy is going to secret nail your prefinished floor down to the osb, on concrete subfloor. Your concrete subfloor seems pretty dry at the moisture content your quoting but you must have a vapour barrier beneath any solid timber in contact with a ground bearing concrete slab- unless there is a ventilated void below (as in the case of traditional suspended timber floors at ground level). I'm guessing your chippy will use a minimum of 8-10 fixings per ply/ osb sheet. I suppose you could try and "seal" the head of each fixing with a patch of duct tape? Before the job starts ask your chippy what his proposal is and post it here for disection! It's a tricky problem and I'm not sure there is a guranteed way to achieve a vapour tight barrier in this instance.
 
Carpenter said:
I'm guessing your chippy will use a minimum of 8-10 fixings per ply/ osb sheet. I suppose you could try and "seal" the head of each fixing with a patch of duct tape? Before the job starts ask your chippy what his proposal is and post it here for disection! It's a tricky problem and I'm not sure there is a guranteed way to achieve a vapour tight barrier in this instance
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Exactly, - he bought 200 fixings for 20 sheets of ply. I know what you're saying (that it is a tricky one). He is starting tonight. If I ring him up to find out his proposal, he might tell me where to go!!!
 
paul5 said:
I need a reducer to go from tiles (about 8mm) to the solid floors (OSB 18mm + boards 18mm). That's a difference of 28mm. I've only seen reducers up to 15mm difference. Are reducers available for a difference of 28mm?
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Just spoke to a timber merchant who didn't have a suitable reducer. He mentioned that there is a place opposite Woodies in Glasnevin who manufacture them. He didn't know their name but he said thats all they do and they sell to the public.
 
OSB3 ply is water proof or resistant and 11mm thick

He can nail that onto battens

He can nail them onto the floor thru the barrier membrane

He can secret nail (porternail) the planks onto the osb3 which comes in 8ft x 4ft sheets
 
OSB 3 boards should not be used on the inside of habitated buildings due to their gassing off, they emmit fumes. It would be illegal, demand the safety data sheet from your trader for further advice.
 
Had my floor glued on to concrete, no membrane, timbers cupped, and floor rising so much I've had to take off doors, also laminate floor rising in adjoining room. Builder says it's the fault of the glue. Any thoughts ?
 
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