Les Solives

[Choochoo]

Hi everyone

Our house did not have a first floor, you looked straight up at the underside of the roof. The necessary beams have been installed by a french artisan ( after a years wait ) and its now time to fit the floor joists, which I will do myself. Can anyone advise me on the correct dimensions of the joists also the spacing between, do they have to be thicker where the bathrooms will be ? Most of the joists will end up being 3.5 metres long approx.

Thanks for your help

John

[Dave&Olive]

hi ok

    you say most of the joists are 3.5 mt long , but whats the longest span ? 

  an  old joiner gave me this ...... twice the span in yards plus 1 gives the size for 2" timber

   so 4 yards wide X  2  + 1 =  9 x2 inch timber , the stock sizes here seem to be 75mm (3 ") so 200x 75 will be ok any longer and i would go up to 225x75.

   you need to set them at 400 centers and square other wise you will  be wasting plaster board when you come to do the ceilings.

 this will be ok for the bathrooms , but would cross lock them if you are  going to plaster board , and sister the joists where the stud walls are going.

  no expert but never had one come down

           dave

 

 

[shimble]

what do you mean by sister the joists?

[Dave&Olive]

[quote user="shimble"]what do you mean by sister the joists?[/quote]

hi

 ok and ooops sorry . his sister ....the main joist and his sister lying by his side. ie 2 together

 if you want to build say a 75 cm stud work wall up from the joist which is only 75cm wide ,where do you nail the floor boards too after.?

  hope this makes sence

    Dave

[shimble]

yep cheers

[Choochoo]

Hi Dave&Olive

Many thanks for the info. The longest span will be just under 3.5m, so 200 x 75 it is.

Thanks also to Dave, who e-mailed me, tried to reply but it bounced back.

John

[Jerac]

The UK building regs contain a table of sizes and spans. A copy is in this site. 

http://www.diydoctor.org.uk/projects/load-bearing_walls.htm