Dry rot and damp

[Carpenters daughter]

We have identified a damp issue which is much worse than we thought. The downpipe from the gutter had been failing for some time (bodge job by the roofers). The frame for the front entrance rotted and we had to get the frame nearest the corner cut out and replaced and had someone in to do the guttering.

We have now found that internally in that corner there is dry rot and damp under the floor boards. The dry rot does not seem to have gone beyond the level of the skirting boards and some of the floor boards in that corner. We have removed the dry rot tendrils and rotting timber ready to treat the masonry and surrounding timber with specified fungicide and will treat the new boards and joists with preserver.

We need to work out where the water is coming from. The picture shows the extent of damp on the foundation under the boards. It has been raining for a few days this week. The down pipe is in that same corner. The downpipe goes to a soakaway (we think). The ground outside is block paving but we suspect that a step put in next to the down pipe and/or where the side gate is, is above the DPC. The DPC seems to be working but in one spot right in the corner it seems to have failed and the timber is rotten above the DPC. The amount of damp ground internally however suggests a far more serious issue than a breach of the DPC. Could it be that the soakaway has failed? Is it time to thrown in the towel and get a surveyor in?

 

[blup]

The dpc may have been bridged by the tiled patio, which in turn sheds water onto the area around the down pipe creating a closer source of damp. The internal pipe under the floorboards may be be blocked or leaking. The down pipe seems newer about four foot up, maybe an old leaking gutter was repaired and the cause is more historic.

 

[Carpenters daughter]

The dpc may have been bridged by the tiled patio, which in turn sheds water onto the area around the down pipe creating a closer source of damp.

Thanks for your reply blup. Yes I think that is likely. The tiled bit is a step under a porch canopy but it still gets wet. Water seems to pool in the area to the right of the downpipe.

 

[Carpenters daughter]

The internal pipe under the floorboards may be be blocked or leaking.

That's the mains gas pipe so we have eliminated that as a possible cause.

 

[Carpenters daughter]

The down pipe seems newer about four foot up, maybe an old leaking gutter was repaired and the cause is more historic.

Definitely been going on for some time, hence the rotting timber but the damp patch is quite marked and seems more defined since we had heavy rain in recent days so we think it's fresh. Going to try and dry it out and see if it comes back.

 

[blup]

Soakaways get blocked by silt etc, so that and the heavy rain is the likely culprit. Would a surveyor help at this stage, or is digging down around the pipe the first thing to do?

 

[Carpenters daughter]

Soakaways get blocked by silt etc, so that and the heavy rain is the likely culprit. Would a surveyor help at this stage, or is digging down around the pipe the first thing to do?

We are going to clear the area around downpipe and take look under the pavers

 

[ree]

OP,
1. There's a gully grill visible at the bottom of pic #2 - why is it there? What is its purpose?
2. Most Down Pipes need to discharge into trapped gullies.
3. Discovering whether your RWP is discharging to a soak-away - or running to a mains drain - or is blocked above or below ground is a simple matter.
4. Where is the nearest manhole?
5. Whats the purpose of the course of bricks at the foot of the gate?
6. The tiled step has sand & cement fillets at the risers, & covering an abutment gap with the wall. Wrong.
8. If you post any more pics please first remove leaves & small plant life for clear views.

9. Inside the house Dry Rot & Dry Rot indications are still showing.
10. Remove the remaining skirting, and hack off plaster to a height of about 400mm in the area of the pic red line.
11. Can you remove the boards etc on the RH. side, and pic further to the right?
12. Close up detailed pics of the bearing joist as it enters the wall pocket might help?
13. Using a flashlight & a small mirror you can see & pic the underside edge of the joists.

 

[Carpenters daughter]

Thanks Ree. Really useful feedback. Answers:
1. Gully purpose - not sure but we think it's a vent for the soil pipe which runs down the side of the house. We are going to test this weekend.
3. Not blocked. This was checked when gutter and RWP was (poorly) replaced earlier this year (we are redoing the guttering ourselves now after a bodge job). We think it runs to a soakaway but will check this.
4. Nearest manhole is the front inspection chamber. Location directly behind pic2 about 2 metres away.
5. Bricks at foot of gate - "decorative" only we think. They are coming out this weekend!
6. Agree!
8. Plant life leaves have been removed (left them in pic in case they were a clue)
9. & 10. Agree. We have removed most of the floor now. We have dry rot treatment and will be treating masonry this weekend.
10. All floorboards and skirting along the front of the room (including around and the other side of the front door) and LHS have been removed. All infected wood joists have been removed. Any remaining wood will be treated with wood dry rot treatment. Wood preserver for new wood.
11. - 13. Will take pics when I get home.

 

[ree]

OP,
3 & 4. Dig out & expose the drainage below the RWP - using a hose, test down the RWP - & observe at the manhole. Flush the WC & observe.
1. Unless things are well wrong, Its not a vent for a soil pipe. It needs digging around to expose it.
10. "All infected wood joists" have not been removed
Dont treat anything until you are more certain of whats going on & why?
Suspicious skirting is plainly visible in pic #1. It needs removing, & inspecting.

 

[Carpenters daughter]

OP,
3 & 4. Dig out & expose the drainage below the RWP - using a hose, test down the RWP - & observe at the manhole. Flush the WC & observe.
1. Unless things are well wrong, Its not a vent for a soil pipe. It needs digging around to expose it.
10. "All infected wood joists" have not been removed
Dont treat anything until you are more certain of whats going on & why?
Suspicious skirting is plainly visible in pic #1. It needs removing, & inspecting.

Sorry these were initial photos. Since I posted them, all skirting has gone Floor boards are gone. I was concerned with source of the damp patch on the floor as a next step. Will take your advice and look at the RWP and suspicious "vent".