damp & dry rot


Old 04-13-02, 08:24 AM
Vic 970
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Question damp & dry rot

Problem of damp & Dry Rot.

The detached dwelling is of a solid brick 9 construction, which does not incorporate a cavity.

Damp has been found in 2 back rooms of the building, 1 on the ground floor and 1 on the upper floor.

On the ground floor the damp is concentrated in the North West corner of the room, consisting of

1: damp at low level, with rotting of the skirting boards and damp and mould patches in the plaster, dpc injection has been applied to the north wall but not the west.

2: tentacles at high level, directly emanating from the upper corner, the tentacles extending for approx 2 feet (0.6 Metres)

On the upper floor tentacles (evidenced from marks in the plaster) emanating from the lower corner, for un-determined length, but giving several damp spots on both the north wall and west wall.


6 10 years ago a broken down pipe was replaced (North wall) and the brickwork
re-pointed (behind the down pipe the plugged joint was about 3 (75 mm) deep.) There was also a large conifer tree close to the west wall, which was removed.


The floorboards (running East West) were removed on the upper floor to give access to the floor joists and void.

Dirty looking cob webby material was found along the North wall, (but much of this is believed to be cob webs) 1 floorboard was found to suffer from dry rot, which was from the West wall and extended about 1 centimetre () there is no other evidence of dry rot, including joists (which extend into the brickwork), floorboards and skirting boards. Nor any signs of damp (either visual or as tested with a moisture meter) to any of the above material or to the brickwork and mortar.

Tightly into the corner there appears to be a lump (covered with cobwebby material) which may be plaster, mortar OR the dry rot organism. This cannot easily be seen (due to accessibility) nor identified.

Further anticipated action.

I intend to carry out the treatment in 2 sections, due to the limitations for storage etc.

Upper room.

1: apply heat from a blown air paint stripper gun to the local area (corner) for a prolonged period of say 2 or 3 hours.
2: remove all evidence and trace of all suspect material with vacuum cleaner.
3: treat wood joists, by drilling to approx 30% depth and injecting (by gravity feed) either a preservative or damp proofer (eg: DPC fluid)
4: remove damaged portion of floorboard (or replace floorboard) and treat local floorboards with preservative or damp proofer (eg: DPC fluid)
5: treat exposed brickwork with DPC fluid.
6: Replace floorboards.
7: remove all affected plaster.
8: treat walls with waterproofer, then apply a coat of synthaproof. Paint with pva adhesive and replaster.

Lower room.

1: Drill and inject DPC fluid to West wall
2: remove all affected plaster.
3: treat walls with waterproofer, then apply a coat of synthaproof. Paint with pva adhesive and replaster.
4: Replace skirting boards.

Note: additional work in the form of replacing a French window along the west wall, by bricking up the bottom and fitting standard window, will be included at this stage.

I would be obliged for any comments on my anticipated course of action, amendments or alternatives.
Plus recommendations of any suitable products.
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Old 04-18-02, 06:38 AM
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Dryrot does not happen where it is dry. It happens when water gets to the wood on a periodic basis, molds, and then dries out.

If you are getting mold on your first and second floor (and there is no third floor), I would say you have a problem with the roof. Roof leaks are natorious for leaking and running down the inside of the roof, hitting the wall, and then running down both the inside and outside of the wall.

Since you have a history of plumbing problems, I would suggest checking the plumbing. This can be done with a pressure test. You plug all drains and revent pipes (and main if you are not on a septic tank). Put air pressure into the pipes and see if it holds pressure. If not, you have a drain pipe that has a hole in it, and is putting moisture into your house.

If your only damage is mold seeping through the paint (floors are not bouncy), you can just apply Kilz to the existing paint and then paint over the Kilz.
Old 04-18-02, 10:31 AM
Vic 970
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Thanks Woodbadger for the reply.

the 'problem' eminates from Between the floors ie: the ceiling level of the lower floor and the floor level of the upper floor. several years ago I replaced a broken down pipe and repointed the bad joints behind it. at the very location on the outside. there was also a large conifer tree growing up the wall (which was removed)

the joists are all bone dry. and the 'lump' that I mentioned turned out to be a lump of mortar (not a fruiting body) there is really no sign of damp, exept in the plaster, where the tentacles are.

one builder said he believed it to be something 'growing' from what the tree had left behind.

but I would like to identify it properly before I move on to repairs.

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