Damp Course Dry Rot Issue

Molep · 22 May 2019 at 14:05

Hi all

noticed some dry rot on my skirting near front door - thought it maybe moisture coming in from round the door - however once skirting was taken off I can see that the previous owners have laid a damp course, cemented over and then laid the floor.

issue with this is that the damp course ends at the wall so any moisture from the ground/floor just escapes here.

Any ideas on what to do?
put new skirting with a few vents in it?

thanks

SeatIbiza · 22 May 2019 at 15:39

What is on the other side of that wall?

The blue sheeting isn't a DPC, it's a moisture barrier for a concrete floor which looks correct. A DPC is for the external walls...

If that wall is an external wall, you're looking in the wrong place for the source of the problem...

Molep · 22 May 2019 at 16:11

OK, that wall is an internal wall shared with next door, it is a cob wall, which is a pain.

I guess it's had the wrong plaster, paint, paper on it not allowing it to breathe

SeatIbiza · 22 May 2019 at 17:04

But unusual to be causing damp itself. It may have been covered with cement which seals it up. What's the outside of your place looking like i.e. the front wall shared between you?

How old is your property?

fastwunz · 22 May 2019 at 17:38

Spores can spread the rot so quite rightly you are tackling it now.

You need to look externally at the walls (pointing, cracking etc) , ground levels and any signs of leaking guttering. Flat roof canopy’s can cause issues too

Molep · 22 May 2019 at 19:35

Outside is all good had gutters, downpipes fixed last year and cleared waterway from downpipe leading out on road. That part of property is about 1800s, if not earlier, the cob wall is about 2ft thick.

Under the wallpaper seems to be plastered, not lime I think and some cement near the bottom.

I think I'll get as much cement as I can off the bottom, take off wallpaper as I hate it and it's knackered leave it to air for a few weeks and put back skirting with a good 1.5" gap behind it. Paper back over. Far from ideal. Don't wanna start ******* about with a cob wall.

Molep · 22 May 2019 at 19:36

Outside is all good had gutters, downpipes fixed last year and cleared warerway from downpipe leading out on road. That part of property is about 1800s, if not earlier, the cob wall is about 2ft thick.

Under the wallpaper seems to be plastered, not lime I think and some cement near the bottom.

I think I'll get as much cement as I can off the bottom, take off wallpaper as I hate it and it's knackered leave it to air for a few weeks and put back skirting with a good 1.5" gap behind it. Paper back over. Far from ideal. Don't wanna start ******* about with a cob wall.

SeatIbiza · 24 May 2019 at 12:06

Yes well being 1800 odd (Georgian) it likely won't have a DPC so if it has been cement rendered this is likely the cause of your problem - the wall can't breath and likely you have double glazing so moisture is contained within the property. Do you have a floor void and are the air bricks in situ and clear? Also, as this is a party wall, it's unlikely there is a damp problem externally and, as you state, all seems ok on the outside. It's a common occurrence with builders these days not having a clue and just cement rendering everyhting as it's cheap and what they know. You see it on repointed walls a lot (don't ask but my company owns about 600 walls) and it actually causes the bricks to detonate as, rather than moisture going out through the mortar, it goes through the bricks and freeze/thaw action blows them apart eventually.

Please, whatever you do, don't get some PCA damp guys in - they WILL say you need a chemical DPC and all that will do is destroy your property.

Molep · 24 May 2019 at 14:24

Ha, no the damp guys can naff off!

We're all single glazed sash with no floor void (I recently fixed under the stairs and it's just earth) so just membrane and concrete on that.

Next door however do have double glazing, wallpaper, gas fire on their side (oldies so like the warm stuffyness) so no moisture can escape there either.

Fitted a drimaster last autumn and that has bought down RH from 70% average to 50% and cleared any condensation, I think that will be enough once its' fully dried after I take off the cement at the base and painted wallpaper.

I read the wallrock paste and paper is supposely breathable (I am not so sure) but it is good stuff to use so will hang that with a natural paint.

Reckon with a bit of airflow behind the skirting it will be good.

Orionaut · 25 May 2019 at 09:34

SeatIbiza said:
Yes well being 1800 odd (Georgian) it likely won't have a DPC so if it has been cement rendered this is likely the cause of your problem - the wall can't breath and likely you have double glazing so moisture is contained within the property. Do you have a floor void and are the air bricks in situ and clear? Also, as this is a party wall, it's unlikely there is a damp problem externally and, as you state, all seems ok on the outside. It's a common occurrence with builders these days not having a clue and just cement rendering everyhting as it's cheap and what they know. You see it on repointed walls a lot (don't ask but my company owns about 600 walls) and it actually causes the bricks to detonate as, rather than moisture going out through the mortar, it goes through the bricks and freeze/thaw action blows them apart eventually.

Please, whatever you do, don't get some PCA damp guys in - they WILL say you need a chemical DPC and all that will do is destroy your property.

This.

Most damp problems on older properties are as a result of using cement over lime mortar.

If yours is an 1800 house, there shouldn't be any cement anywhere. any that is there should really be removed.