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Damp proofing quote check: when you do not need a new damp proof course
A quote for a new damp proof course, usually injection plus a metre of hacking off and replastering, is one of the most common bills Kent homeowners are presented with. Sometimes it is the right job. Often it is not. This guide sets out the cases where a new course is unnecessary, the questions to ask, and how an independent check works.
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What a damp proof course does, and does not do
A damp proof course is a horizontal barrier near the base of a wall that stops ground moisture rising. It does nothing for rain coming through the wall, for water from a leaking gutter or pipe, for condensation, or for ground that has been raised above it outside. If the wall is wet for any of those reasons, a new course will not help.
When you probably do not need one
In each of these, the cause is something else, and the fix is usually cheaper: lowering the ground, repairing rainwater goods, repointing in the right mortar, improving ventilation or replacing salt contaminated plaster.
- The house was built after about the 1920s and has a visible course that is intact
- A path, patio, drive or flower bed sits at or above the existing course
- The damp is worse after rain or sits under a gutter, downpipe or window
- The damp is on an upper floor, a chimney breast or an internal wall with no ground contact
- The problem is black mould on cold walls and around windows
- The wall is solid stone, flint or timber frame that was never built with a course and stayed dry for a century
When you might
A solid walled house with no course, or one that has genuinely failed, standing on damp ground, with damp at the base of the walls that falls off with height, is present through the year, and remains once the external causes have been dealt with, may need a new course. That is a minority of the walls we are asked to look at, but it exists, and when we find it the report says so and specifies it.
Questions to put to the firm that quoted
A good contractor will answer these readily. If the answers are vague, or the pressure to sign is high, get an independent opinion.
- What is the cause, and what is the evidence?
- What did you find outside: ground levels, gutters, pointing, render?
- How did you rule out condensation and penetrating damp?
- Why this height of replastering, and why this plaster on this wall?
- What exactly does the guarantee cover, and who stands behind it?
- Can I have the survey and readings in writing?
How our quote check works
Send the quote when you book. We survey the property, inside and out, and the report says which parts of the quote are supported by what we find, which are not, and what else should be done first. We carry out no remedial work and take no commission, so we have nothing to gain from either answer. Our fees are on the prices page and are fixed before we come.
Questions
The firm offered a 30 year guarantee. Does that mean the work is needed?
No. A guarantee covers the treatment doing what it claims. If the damp has another cause, the treatment was never the fix and the guarantee will not help.
Is it worth paying for a survey to check a free quote?
Usually, yes. Our fee is a small fraction of a typical injection and replastering job, and the check often removes most of the work.
Can I fix bridging myself?
Often. Digging a path or bed back to two courses below the damp proof course, or adding a gravel strip, is within reach of many homeowners. The report tells you what is needed.
What about replastering?
Salt contaminated plaster may need replacing even when no new course is needed. The report says where and with what, because the wrong plaster on an old wall causes its own problems.
What if you agree with the quote?
Then the report says so, with the evidence, and you can go ahead with confidence.
Do you cover all of Kent?
Yes. See our areas page for town by town notes.