Dry Rot in Masonry

samfc13

I live in a terraced house (approx. 100 years old) and I've found some Dry Rot coming out of the adjoining brick wall between my neighbour's property and mine. I cannot however find any infected wood. I've stripped back all the plaster, wood, etc. right to the external wall. I've also been and checked my neighbours who does not have any sign of it either. I'm no expert but it was my belief that Dry Rot needs wood to feed on and shouldn't be able to grow on mortar. I'm at a loss to think where the Dry rot may be feeding.

The only space between the two properties would be the disused chimney flues. One of these has not been capped and the fireplaces have not been vented where they were blocked up. Could this be the source of the Dry Rot?

I would be very grateful for any help/suggestions people could give as it's driving me crazy!

27col

If there is no wood involved. How do you know that it's dry rot.

Hoploz

I'm a bit confused by the geography of the wall - you've stripped back to the external wall, but there's a chimney between the houses? But I would ask if it could be possible things have dropped down the chimney and be causing problems at the base? But that would presumably only affect the base of the chimney not an outside wall.

keith969

I had dry rot in a 1860's house I once lived in. There was a leak in the (flat) roof above a bathroom and it was behind the shower tiles, in the lathe&plaster wall etc. It likes a damp, poorly ventilated space to grow in and needs wood although the strands can go through or cross masonry, so what you are seeing may have its source some distance away.

You need to find the location of damp wood - might be under floorboards, in the ceiling joists. Unlikely to be in a chimney but dampness from this may be affecting adjacent wood.

If you get a specialist in, beware - they will usually try and sell you an expensive treatment. I did it myself (apart from the leaky roof, which was replaced) but it was a lot of work.

samfc13

Thanks for the answers. I'm pretty sure it's dry rot as saw the rust coloured fruiting spores in the mortar between the bricks. They weren't too big only 1-2 inches across but seemed to match pictures of dry rot I've seen.

The rot is in the corner of the house where there was originally a press cupboard so has affected one wall which is external to the rear of the property and the other which is the adjoining wall to the neighbour.

There has been a bit of rot in a joist and in the lintel above the press cupboard which I am getting replaced but I think that was wet rot as didn't have any of the cracking associated with dry rot. All other wood I can see looks pretty sound.

There had been some leaking in the roof above the area affected which has been repaired. The pointing was also repaired in the portion of the external wall that was damp and is slowly drying out. (This is taking ages as it is the external sandstone wall and it never stops raining in Scotland!) The only thing I can think of where water could still get in is the chimney flue.

I've searched for rotten wood round the affected area to a distance of a couple of metres; should I be looking further away as well? All the strands from the rot seem to be coming from the adjoining wall. Does it sometimes travel in circuitous routes?