Raising timber floor level.

eamon11

hello folks,

I am raising the floor level 4 " on a 1940 house. I will be using 4" joists on the original concrete floor. One room however already has a joist timber floor. This was an extension done in the 60 s. When I raised the floor boards, the joists next to the external wall have some rot.
Anyway, in order to raise this floor, is it ok to lay joist across the original joists?

Thanks in advance.

Eamon

sky6

You should take the rotten one's out and replace them otherwise you're only inviting trouble. If It's not a big area I'd replace all the old with new Treated Timber.
For the couple of hours work and small cost involved it's not worth it.

jack of all

You need to investigate further why rot occured in the first instance- due to lack of DPC/ DPC bridged, lack of ventilation/ original vents closed up/ obstructed etc? Was ground level externally raised up, does ground or path bridge DPC? All basic issues which can lead to rot in suspended timber floors. If basic good building practice in relation to DPCs and ventilation are ignored you will get wood decay and worse, so examine the area thoroughly and if in doubt ask a knowledgeable person (competent builder or tradesperson) to advise.