Damp wooden sub-floor

[MrHfromBath]

I have just moved into an old house with spongy floorboards. It was picked up in the survey and is no surprise as there is poor sub-floor ventilation, which I am rectifying.

I can feel that the joists in the corners are rotten and the plate that holds up the joists is also rottn to a lesser extent. I want a good job, without paying the earth.

The 2 rooms affected are roughly 4x5m, with bay windows.

How would you approach this job and roughly ow long would it take/would it cost assuming that the damp is limited to the edges and corners, as it seems to be. I want a proper job, which will last as i intend to stay in the house for good.

Thanks for all advice.

 

[gregers]

take up as much of the floor to gain as much access as needed,if its just the joist ends that are shot then 1 way of sorting this problem out is,
jack up the joists with a car jack and a couple of lenghts of timber remove old plate clean out all debris including mortar bed where plate was,cut off the rotton bits of off the joists.making sure they are still long enough to sit on the new plate?
cut/treat and wrap new plate with dpm (bottom and back)bed new plate down with new mortar gently let the jack down but not totally so they find the correct level once dry take jack away.

another way
if your joist ends are really rotton then it may be neccessary to replace back to the next plate/sleeper wall.