is 1/2" shuttering ply good enough

andyone

ok, i'm flooring my attic space, 16" centers and i was wondering will 1/2" shuttering ply do the job.... i'm making two bed rooms, so they'll have the usual furniture in them, and a large games/media room...... which would have maybe a couch or two in it..... i'm not over worried about the finish as it will be carpeted at some stage.... as always price is an issue..
any advice would be welcome..

looksee

Half inch is ok if you are just using the attic for storage, I think you would need 18mm which is more like three quarter inch for usable rooms. Presumably you are working on rafters that are intended to support living space?

andyone

ha ha , of course i'm not.... my origanal builder was and i'm sure still is a w******, but i have crossed layed the original joices with 2"x2" battons.... i.m.o. strengthening the whole project......

mp22

3/4 osb board in 8 by 2`s(feet) might help with the costs,they really must be going on 9 by 2`s(inchs) to support bedrooms.

slavetothegrind

Andy you need to get advice there, all the 2x2's did is increase the loading on the already weak floor.

Maybe move to construction and planning where you will get good advice from qualified peeps.

cork2

hey. dont dream of using anything less than 3/4" sheets and the best you will get is osb tongue and groove. they come in sizes 8x4 and 8x2. the 2x2 baton will only really spread the weight over the floor area. what size are the actual floor joists, how far are they spanning between the interior load bearing walls and how much insulation is between them?

andyone

cork2 wrote: »

hey. dont dream of using anything less than 3/4" sheets and the best you will get is osb tongue and groove. they come in sizes 8x4 and 8x2. the 2x2 baton will only really spread the weight over the floor area. what size are the actual floor joists, how far are they spanning between the interior load bearing walls and how much insulation is between them?

ok ok did you ever get that sinking feeling....... the original joists 6"x2" spanning across 13 feet from exterior wall to an internal wall(the hall running the length of the house.....) the usuable space in the attic only stretch's ....maybe 8 feet either side of the internal hallway.......so at no point is a full room or any thing like it directly over a down stairs room .... i know its borderline but if i starve my kids it should work....???
osb tongue and groove..???? any idea of the price of the 8x2 sheets as these would be easier to handle....8x4 shuttering ply in 3/4" locally is just over the €20 mark..

thamks to one and all for your comments....

cork2

6x2 spanning 13feet is dodgey to say the least. your roof wasnt designed to be converted obviously. by putting weight on that floor your liable to crack all your ceilings downstairs aswell as them sagging.6x2 unsupported really shouldnt span more than 8 or 9 feet.

andyone

cork2 wrote: »

6x2 spanning 13feet is dodgey to say the least. your roof wasnt designed to be converted obviously. by putting weight on that floor your liable to crack all your ceilings downstairs aswell as them sagging.6x2 unsupported really shouldnt span more than 8 or 9 feet.

ok ... the space upstairs is spanning 14 ft...... underneath the centre of this space is a hall way, with two supporting walls either side.... so give or take you have at most 5-6ft of the floor above, being over a room below..... do you think my 2"x2" battons helped spread the load a little.... and then if i use the 3/4 osb ply .... will it not help spread the load futher.....????

cork2

andyone wrote: »

give or take you have at most 5-6ft of the floor above, being over a room below

thats not too bad. ya the combination of the batons and osb will help. make sure the osb is tongue and groove and glue all the joints (nobody glues osb but if you check the manufaturers recommendations they state it should be glued and it makes a huge difference to you overall floor.) also screw down the osb as driving nails or using nailguns can crack the downstairs ceilings and pop all the slabnails.

sunnysoutheast

andyone wrote: »

ok ... the space upstairs is spanning 14 ft...... underneath the centre of this space is a hall way, with two supporting walls either side.... so give or take you have at most 5-6ft of the floor above, being over a room below..... do you think my 2"x2" battons helped spread the load a little.... and then if i use the 3/4 osb ply .... will it not help spread the load futher.....????

Have you checked that the attic complies with building regs. for a habitable/living space conversion? Cracked ceilings may be the least of your worries!

FWIW when we got our loft converted in London we had to put a brand new floor in, suspended over the original one, from two steel RSJs. Made the house much warmer too!

SSE

andyone

thanks for that cork............. i'm a red blooded male.... there will be no nailing,,,,, just screwing all the way...... as for building reg's SSE, what are they.....i'm just flooring the attic for storage if any one ask's ya..... and @800 square foot..... there'll be loads of room..:cool::cool::cool:

looksee

Someone said that about building regs near us, and raised the roof of a single storey house in order to put in another couple of rooms in the attic space. Then they tried to sell it, but the over-heavy roof was pulling apart and the gable wall was splitting, you did not have to be an engineer to see what was happening. I don't know whether it was ever sold but it was on the market for a very long time.