floor span

[kent tiler]

as im replaceing the joists and the old floor say the room is no more then
1700mm(w)/2700mm(L) at 400mm centers what size joists do i need i was trhinking 50mm/100mm(2+4ins or is that too small im puting in nogins too as its supporting a bath its a ground floor flat and all the joists and floor boards are roten :mad2: so its new joists and T&G chipboard flooring going down:smilewinkgrin: i dont want bownce in the floor as im tiling it soon after

if i dont get a ts60 bythen ill be using my ts40 ha harrr:

 

[White Room]

Re: floor spane

Why use chipboard rather than ply

 

[kent tiler]

Re: floor spane

I can its just is T&G thort its stronger thats all i just dont know the size of joists too use its doing my sweed in so i can price the floor in

 

[peckers]

Re: floor spane

What size are the joists you taking out? is there any deflection in the floor before they were removed I would say 5x2 would be better (but im not sure) noggins at 300 centres use ply as white beam has said as chipboard is not stable enough to tile onto

 

[kent tiler]

Re: floor spane

so its 5+2 3m lenths what sort of price are 5+2 joists then

 

[mikethetile]

Re: floor spane

you require 2x8 for floor joists and you need to ring your local timber supplier for a price

 

[kent tiler]

Re: floor spane

woooooooooooooow that thick thats a bit big is that 600mm centers think im looking to get 10/ 3m lenths

 

[peckers]

Re: floor spane

you require 2x8 for floor joists and you need to ring your local timber supplier for a price

I knew someone would know

 

[Colour Republic]

Re: floor spane

Exactly how do plan to remove the joists and replace? You saying these joist only form part of this room?

 

[Rob Z]

Re: floor spane

The four S's are what you need to consider when sizing floor joists: span-species-spacing-size.

Span-what is the unsupported span of the joists?
Species-what is the species and grade of the lumber?
Spacing-what are centers for spacing the joists?
Size-what is the size of the joist (depth)?

I agree with Mike-I can't imagine any floor joist being adequate that is less than a minimum 2 X 8 and 16" o.c.

There are "Deflecto-meters" available on the web, and you can input the data for your floor and get the calculated deflection rating. The number used here in North America is a minimum of L/360 for ceramic. I've never seen this discussed here on the site but the same principles must hold true in the UK for floor framing.

 

[jay]

Re: floor spane

its amazing just how much a tiler has to know to do a job:lol::8:

 

[faithhealer]

Re: floor spane

Only replaced joists the once and called a mate in to give a hand because I would have been there all week trying to figure it out. Learnt a lot about wood worm and rot that day

 

[Rob Z]

Re: floor spane

John, one of my first paying jobs was framing houses, so I have a bit of experience with this...it helps out because when a floor needs work it keeps the income coming to me and my employees rather than another contractor.

 

[mikethetile]

Re: floor spane

the states and canada are streets ahead of the uk on timber frame building and understand timber and how it behaves

that knowledge is limited in the uk as we are mainly masonry built, even timber frame is masonry clad which has caused all kinds of problems over the years

both Robs are right, its not as simple as ripping out and replacing. its structural work and needs to be treated as such

one question that hasnt been answered is why the joists need replacing

are the undersized and cant take the weight of a bathroom or have they rotted

if rotted ...........why

it the walls are lathe and plaster , have they been built across the joists

will cutting the joists out jeapordise the integrity of the building

this is work for a fully insured registered builder that understands structural work and has the experiance to deal with this kind of work safely

 

[Aston]

Re: floor spane

they seem to frown at 8 x 2 floor joists in canada, they always recommend 10 x 2's
is the us the same rob?

ps, agree with mike on the us / canadian framers

usa / italy / australia/ all have great tiling reputations too...