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Hi
We have recently moved in to a mid terraced brick built house that is just over a hundred years old. Some wet rot and beetle activity were apparent in the front room at the bay window, which is north facing. This was all known about before the purchase, but now is the time to fix it. I have lifted half of the floor boards to get a better look at the joists.
The front-most joists are in poor condition and will need replacing. The other joists run across the full width of the room, with a brick support running down the centre of the room. I have lifted boards between the centre support and the hallway. The joists look mostly ok - but the hallway ends sit on a brick step, on top of of which sits a piece of wood, which is what the joist ends rest upon. This piece of wood, and the floorboard above, has allowed the rot or the bettle to move into the end of most of the joists.
I can spot parts which bit definately need replcacing, but would like some help on what is ok and the method to use for rebuilding...
Should I bring up the rest of the floor boards to check the joists and supports at the other side of the room? The bay needs attantion, but the rest shows no signs.
Should I replace the whole joist, the half room width of joist, or just the rotted ends?
How should the joists be supported and fixed to the walls? Using the same brick step and timber leveller method or not?
I am expecting to use treated timber for the joists, but should any new or existing floorboards be treated? Will the area in general require treatment?
Should I use a moisture barrier at any point?
I'm happy to email photos...
Thanks for reading, I hope there is some knowledge out there to tap.
The timber leveller, or wallplate, sounds like it should be replaced.
I would lift all the floor and look but just cut out and splice in new timber where existing is rotted/decayed.
Like-for-like replacement in terms of the construction I would have thought.
Renew the boards with treated timber. Perhaps the dampness has come from the underbuilding/dwarf walls. Maybe the damp proof course needs replacing. If so, renewing the timber won't address the route of the problem. If you need to replace the DPC then maybe take the opportunity to treat the substructure brick with something like Thompsons waterseal or something.
Check the dwarf wall brickwork to see if it's dry. Sounds like it's fine if the timber in the centre of the room is unaffected.
Pretty much what grantus has said - plenty of good advice there. I'd also check all ventilation bricks at front and back of house and make sure these are all open. Victorian houses are designed to "breathe" under the floors front to back of house.
Sounds pretty much par for the course of a lot of houses of that age when I'm rooting around underneath joists etc. It's possibly something to not get overly concerned about.
Using the same brick step and timber leveller method or not?
Yep, probably best to replace any of those to which you have access with treated (tannelised) boards.
Should I replace the whole joist, the half room width of joist, or just the rotted ends?
This is entirely up to you, but I'm guessing replacing one whole joist will require you to lift pretty much the whole existing floor...which may or may not be a ball-ache of a job.
Where you chop off the existing joist, overlap your new piece with the old by around twelve inches and join with coach bolts - a bit more work, but the proper way to do it. Support the join with bricks...pieces of slate are handy as packers. Make an attempt to get the joists level, otherwise you'll be plagued by squeaks. Also, unless you're planning to sand back the floorboards, use 60/70mm No.10 screws to fix the floorboards back down.
when relaying the new ends onto the 'brick step' make sure you run a new DPC along it first, same with the sleeper wall. If not possible with ex joists put square/rectangluar bits of dpc or use slate packer under each joist. The house won't have a dpc at all so you are trying to isolate any new timbers from the substructure(sleeper wall stepped which might have damp coming up from the ground/solum).
splice new ends as above and definitely make sure the vents are clear, very important as this combined with some rising damp is one of the main causes of rotting floors in houses of this age. depending on the size of the room its actually sometimes easier just to take the lot out and start again?? But thats up to you