DPC height quandry

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jimpom23
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DPC height quandry

Post by jimpom23 » Sat Jan 20, 2018 1:30 pm

Hi,

I have damp on the front wall in the front room of my 1900 terrace (the left side of the window as you look at the picture below) and having had an independent survey done it was suggested that a DPC is done and a channel dug out at the front to alleviate breaching of it from splashback.

See picture which shows the mortar lines I am discussing below - they are essentially the ones above and below the grey box on the wall on the right of the picture.
dpc.jpg
dpc.jpg (65.29 KiB) Viewed 1254 times
As an enthusiastic DIY'er I decided I would do this myself, the wall is less than 5 metres in length and having researched them, I decided on dryrods so simply need to drill the right holes - no worries.

I started to prep the area at the front of the house before making a start on the digging of a trench/channel but on moving back the aggregate and crud I found that it was solid stone there which pretty much stops me dead with regards to digging out a channel to maintain the 150mm clearance from ground level.

As I see it, I now have two choices:

Install DPC at the loweer point which seems to be at or just below floor level - I feel this would be most effective as it is below floor level/skirts. OR

Install DPC at next mortar line up which takes it roughly 2/3 inches above the skirting board, so about a foot above floor level. This would meet regulations of being 6 inches above ground level but I'm guessing won't do much for the damp.

The best way to remedy the issue overall I think is to do the lower of the two lines as it would be most effective but I'm conscious that we want to move and the first thing a surveyor would say is that it is less than 6 inches above ground level so is likely to be breached. I should also add that I plan to paint the entire of the front of my house in safeguard stormdry so am hoping this would help.

I would appreciate any advice anyone has.
Last edited by jimpom23 on Sat Jan 20, 2018 2:14 pm, edited 1 time in total.
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steviejoiner74
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Re: DPC height quandry

Post by steviejoiner74 » Sat Jan 20, 2018 2:02 pm

The fact it’s a solid wall doesn’t mean you cannot inject with cream/paste or dryrods. Who told you this wasn’t possible?
Here are the drilling guides for these different wall thicknesses.
Depth of solid wall 4½″ (115 mm) 9″ (230 mm) 13½″ (345 mm) 18″ (460 mm)
Depth of Drill Hole 95 mm 210 mm 325 mm 440 mm
Hole Intervals 120mm
Drilling is done from outside and if you go down the cream route it’s an easy diy install.
Carpentry,I can explain it to you but I cannot understand it for you.
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Re: DPC height quandry

Post by jimpom23 » Sat Jan 20, 2018 2:16 pm

steviejoiner74 wrote:The fact it’s a solid wall doesn’t mean you cannot inject with cream/paste or dryrods. Who told you this wasn’t possible?
Here are the drilling guides for these different wall thicknesses.
Depth of solid wall 4½″ (115 mm) 9″ (230 mm) 13½″ (345 mm) 18″ (460 mm)
Depth of Drill Hole 95 mm 210 mm 325 mm 440 mm
Hole Intervals 120mm
Drilling is done from outside and if you go down the cream route it’s an easy diy install.
Hi Stevie - it looks like I wasn't clear, I have edited the message in an attempt to make more sense!

The issue is that I was planning to dig out a channel to ensure the lower level mortar line could be used and DPC would be 150mm above ground level but with it being stone on the ground right up to the house I'm reluctant to even attempt cutting into stone.

It may be that this is my only real option if I opt for the lower of the two mortar lines - just means I will have to get someone in to do it.
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Re: DPC height quandry

Post by wes56 » Sat Jan 20, 2018 6:56 pm

i dont have much faith in chemical injectio or DPC rods.we have worked on damp an timber jobs lots of times an ive yet to see proof that the rods or chemicals work.
one house had 3 rows of historic injection holesinside and outside in a solid wall, rising damp was everywhere.outside the house looked a joke.
but i was told that the rods are the best of a bad job at least you dont need all the injection gear.
can you drill a hole in a mortar bed an put a plastic plug in it? then you can insert rods.
DPC's should be below the joist seats or at least well below the finished floor.

what we do, like lots of builders, is to hack off all bad plaster and render in sand an lime. this stops the salts coming through for years.
you should check the joist tails an skirting in that damp wall maybe theyve rotted.

examine the bottom of the down pipe thats blocking an air brick, there might be leaking goin on.
do you have a clear throating in your stone window sill?
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Re: DPC height quandry

Post by jimpom23 » Mon Jan 22, 2018 9:38 am

wes56 wrote:i dont have much faith in chemical injectio or DPC rods.we have worked on damp an timber jobs lots of times an ive yet to see proof that the rods or chemicals work.
one house had 3 rows of historic injection holesinside and outside in a solid wall, rising damp was everywhere.outside the house looked a joke.
but i was told that the rods are the best of a bad job at least you dont need all the injection gear.
can you drill a hole in a mortar bed an put a plastic plug in it? then you can insert rods.
DPC's should be below the joist seats or at least well below the finished floor.

what we do, like lots of builders, is to hack off all bad plaster and render in sand an lime. this stops the salts coming through for years.
you should check the joist tails an skirting in that damp wall maybe theyve rotted.

examine the bottom of the down pipe thats blocking an air brick, there might be leaking goin on.
do you have a clear throating in your stone window sill?
Hi Wes, good point on the soil pipe, will have a closer look.

Forgive my ignorance, is throating a channel or similar cut into the base of the sill on the outside? It doesn't appear to have anything like that.
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Re: DPC height quandry

Post by ayjay » Mon Jan 22, 2018 9:55 am

jimpom23 wrote: Forgive my ignorance, is throating a channel or similar cut into the base of the sill on the outside? It doesn't appear to have anything like that.
Yes, a drip groove, any water running from the top of the cill meets the groove and then falls off, without a drip groove the water just runs to the wall underneath the cill and then down the wall, if the joint under the cill where it meets the wall is at all suspect the water will also run inside.
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Re: DPC height quandry

Post by jimpom23 » Mon Jan 22, 2018 10:09 am

ayjay wrote:
jimpom23 wrote: Forgive my ignorance, is throating a channel or similar cut into the base of the sill on the outside? It doesn't appear to have anything like that.
Yes, a drip groove, any water running from the top of the cill meets the groove and then falls off, without a drip groove the water just runs to the wall underneath the cill and then down the wall, if the joint under the cill where it meets the wall is at all suspect the water will also run inside.
Thanks ayjay - I will remedy that
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Re: DPC height quandry

Post by Cantseeitfrommyhouse » Mon Jan 22, 2018 11:22 am

wes56 wrote:i dont have much faith in chemical injectio or DPC rods.we have worked on damp an timber jobs lots of times an ive yet to see proof that the rods or chemicals work.


what we do, like lots of builders, is to hack off all bad plaster and render in sand an lime. this stops the salts coming through for years.
you should check the joist tails an skirting in that damp wall maybe theyve rotted.

examine the bottom of the down pipe thats blocking an air brick, there might be leaking goin on.
do you have a clear throating in your stone window sill?
:thumbleft: :withstupid:
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Re: DPC height quandry

Post by wes56 » Mon Jan 22, 2018 7:43 pm

whats the sign im with stupid mean?
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Re: DPC height quandry

Post by moderator2 » Mon Jan 22, 2018 8:08 pm

wes56 wrote:whats the sign im with stupid mean?
It means I agree with the above
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