Chemical DPC on Rendered Property - Without removing render??

Shane Hart

New Member
Hi
I live in an old property (roughly 1730 with thick walls, no idea of composition), it has been extended about 25 years ago so some parts are normal brick cavity walls. Entire property is rendered. There are a couple of places where I have had damp and want to put in chemical DPC, last done 1995. Really don't want to strip back render. Is it ok to inject into brick or does it have to be into mortor? Any recommendations on what chemical cream/solution to use greatly appreciated!
Thanks
 

JML

Member
1730 solid brick walls with lime mortar. Firstly I’d try and lower the water table around the the property and thus the hight damp rises within the walls,
By installing a drainage system ,if possibly. Otherwise a water based chemical injection system, preferably into the mortar line, although you may have to remove a band of render, first. Then reinstate with bell cast bead at the injection line. Hope this helps.
 

D-I-Why

New Member
Chemical DPC is the wrong approach. You need to work out what the cause of the damp is. Is it penetrating or condenstation ?
If a cement render then that's probably not helping but check the ground levels, check the overhangs, gutters, make sure your drains actually drain and no cracks to the clay pipes - any trees close to the house will cause all sort of issues due to root infultration.
What kind of floor? suspended or filled in with concrete? Not uncommon for solid floors to cause bridging.
 

Tom_MidlandDamp

New Member
Hi
I live in an old property (roughly 1730 with thick walls, no idea of composition), it has been extended about 25 years ago so some parts are normal brick cavity walls. Entire property is rendered. There are a couple of places where I have had damp and want to put in chemical DPC, last done 1995. Really don't want to strip back render. Is it ok to inject into brick or does it have to be into mortor? Any recommendations on what chemical cream/solution to use greatly appreciated!
Thanks
Throw a ventilation unit inside to help manage moisture internally and if accessible, throw a gullie drain in around the property to releave pressure off the wall.

Does it also have Lime plaster?
 

brimplas1

Well-Known Member
Chemical DPC is the wrong approach. You need to work out what the cause of the damp is. Is it penetrating or condenstation ?
If a cement render then that's probably not helping but check the ground levels, check the overhangs, gutters, make sure your drains actually drain and no cracks to the clay pipes - any trees close to the house will cause all sort of issues due to root infultration.
What kind of floor? suspended or filled in with concrete? Not uncommon for solid floors to cause bridging.
Or capillary?
 

worthwords

Active Member
Hi
I live in an old property (roughly 1730 with thick walls, no idea of composition), it has been extended about 25 years ago so some parts are normal brick cavity walls. Entire property is rendered. There are a couple of places where I have had damp and want to put in chemical DPC, last done 1995. Really don't want to strip back render. Is it ok to inject into brick or does it have to be into mortor? Any recommendations on what chemical cream/solution to use greatly appreciated!
Thanks
Essentially don't. you are looking at a solution rather than the problem.chemical DPC is expensive, never considers the underlying cause = usless and likely to be damaging to old properties.
 
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