Suspended floor replacement

[empty_vessel]

I've recently moved into a Victorian semi and have discovered that the front room floorboards and joists have wet rot. I need to replace the boards and joists but have no idea where to start!

I know I need to get some more ventilation sorted to stop the rot coming back so I'm going to try and put in some telescopic underfloor vents (a recent driveway alteration appears to have raised the level outside so straight through air bricks are no good).

Some of the boards were lifted to diagnose the problem, is the next step to remove everything and get some new joists? Obviously I'm a bit new to this DIY game so I need some guidance, any help is greatly appreciated!

 

[JohnD]

fix the damp before you replace the timbers, or the new ones will go rotten too.

 

[empty_vessel]

When you say fix the rot, what do you mean? I thought removing all of the affected boards and joists, then fitting the additional vents would stop the rot in its tracks, is this not the case?

If I need to get some kind of fungicidal treatment for the building I'll probably need some professional help! I'll hopefully find a builder to give me a hand, this job sounds like its growing to be a big one!

 

[JohnD]

I said fix the damp first.

 

[masona]

The most common problem are the wallplate that the floor joists rest on, poke it on the side with a small screwdriver, if it's spongy or soft then will need whole new flooring

 

[empty_vessel]

I said fix the damp first.

Sorry, I need to read posts properly! I'm just going to put the vent bricks in first and remove the floor, leave it for a couple of weeks to dry up then look at sorting the floor once the area is dry. Hopefully this will sort the problem.

 

[JohnD]

you need plenty of vents at front and back of house to get air movement. Older houses are generally built with too few, and you need extra because you already have a damp problem that needs drying out.

Sometimes in older houses when you lift the floorboards you find bare earth or damp concrete. This can be covered with polythene and new oversite concrete to reduce the amount of damp that comes up from the ground (this will be easier if you are lifting the floors)

 

[JFC]

If the new driveway has been built right up to your property you need to cut it back so its not bridging the damp course . Dig a trench and back fill with pea shingle , a brick wide would do and this will also allow you to block out the pea shingle where your new vents will go .
Cut your floorboards right back to 1m after the last infected rot and number your boards as you go . Cut your joists back to the last sleeper wall or wall plate that is sound . Remove the rotten wall plates but try and leave the mortar course it is sitting on (it will make your life easier) Put DPC over the mortar course before new wall plates go on .
Have a look at the mortar course , if it looks shot then rebed the plates . If its that bad it will fall away anyway . Dont forget to clear the oversite and chemical treat the whole area .