Damp proofing in Sevenoaks? Get an independent survey first

Why the survey comes before damp proofing in Sevenoaks

Damp proofing is the answer to one specific fault, a missing or failed damp proof course, and that fault is far rarer in Sevenoaks than the quotes suggest. Before anyone drills a wall, somebody with nothing to sell should establish why it is wet. That is the whole of what we do. We carry out no treatment, so the survey is not a route to a sale.

The quotes we see most often in Sevenoaks are injection and cement replastering on solid walled period houses, timber treatment of whole roofs on the strength of old flight holes, and tanking of cellars that were never meant to be dry rooms. In each case the real issue tends to be rainwater, ground levels, ventilation, or the use the space is being put to, rather than a failed course.

Injection, tanking, membranes: what they are for

Injection is for rising damp: groundwater drawn up a wall that has no working course. Tanking and cavity drain membranes are for walls below ground that hold back soil and water, such as cellars and basements. Salt resistant replastering is for walls where years of damp have left salts in the old plaster. Ventilation is for condensation. A quote that applies one of them to the wrong problem will fail however well it is installed.

In Sevenoaks the commonest mismatch we see is injection and a cement based replaster on a wall whose real trouble is outside: open joints, raised ground or a leaking downpipe. Fix those and the wall often dries without anything being injected at all.

Sevenoaks walls, and what they actually need

Ragstone, tile hung, weatherboarded and timber framed walls all need to breathe. They need lime pointing and plaster, sound boarding and tiles, gutters that work and ground kept down. The interwar and post war houses near the station have cavity walls and courses that work when they are not bridged. In both cases, the damp proof course is rarely the point.

Sevenoaks stands on the Lower Greensand, the Hythe Beds of sandy limestone and ragstone that form the ridge, with Gault clay in the vale below at Otford and Kemsing and the chalk of the North Downs beyond. The greensand drains freely, so on the ridge damp is usually rainwater rather than ground water. Springs break out where the sands meet the clay, and houses along that line, and in the Darent valley, can sit in much wetter ground.

• Maintaining weatherboarding and tile hanging so they shed water, and keeping ground clear of the sole plate
• Repairing valley gutters, parapets and hoppers on large period roofs
• Lime repairs on ragstone and timber framed buildings instead of cement and injection
• Targeted timber treatment only where activity is confirmed, after the moisture is dealt with

Oasts, barns and conversions

Converted oasts and barns are common around Sevenoaks, and they are often quoted for damp proofing when damp appears. The original buildings were agricultural and were never meant to be warm, dry and sealed. The conversion added insulation, plaster and windows, and often closed up the ventilation that kept the structure dry.

Damp in a conversion is therefore usually a question of how the wall build up was designed: whether insulation sits directly against a single skin wall, whether there is a cavity or membrane, and whether moisture can escape. Injecting the wall rarely addresses any of that. The survey looks at the whole wall and recommends changes that let it dry.

The signs of a damp proofing job worth paying for

• The contractor can tell you the cause in a sentence and show you the evidence
• The quote mentions what is happening outside the Sevenoaks house, not only inside
• Plaster removal is limited to where salts actually are, with a height that matches the readings
• Materials are named and suit the wall, rather than a standard system applied to every house
• The guarantee is insurance backed or otherwise protected, and states exactly what it covers
• Nobody pressed you to sign on the day

Red flags in a damp proofing quote

• A diagnosis of rising damp from a single meter reading
• No mention of anything outside the house
• Injection recommended on internal walls, chimney breasts or walls above ground floor
• A discount that expires today
• Treatment of woodworm or rot in every timber "as a precaution"
• A quote for a Sevenoaks period house that would be identical for a 1990s semi

When a damp proof course is the right answer

Genuine rising damp exists, and when the survey finds it the report specifies the remedy plainly. The test is not a meter reading but a pattern: damp highest at the base of the wall, falling with height, present on walls with no external fault, and present in summer as well as winter. In Sevenoaks we find that pattern on a minority of the walls we are asked about.

Our survey fees are published on the prices page and fixed before we visit. Set against a damp proofing job on a Sevenoaks house, which typically runs to several times that once plaster removal and making good are included, the survey is small. When it shows that a wall needs a gutter repair rather than an injected course, it pays for itself several times over.

Buying in Sevenoaks often means a substantial period house or a cottage in one of the villages, and a building survey that recommends specialist investigation of damp and timber. Commissioning that from a firm that sells treatment invites a long quote. An independent survey tells you what is active, what is historic and what is simply maintenance, so the negotiation is about real costs.

The report is yours to use as you like: to compare quotes, to put to a seller or landlord, or simply to know. We take no commission and recommend no contractor, so you choose who does any work in Sevenoaks, and we will read their quote against the report if you ask.

For the full picture of what a survey here involves, see damp surveys in Sevenoaks.

Around Sevenoaks

The High Street and Kippington

Listed and conservation area buildings in the centre, large period houses to the west. Rainwater, render and cellars dominate, and recommendations are written with consent in mind.

Riverhead and Dunton Green

Victorian cottages and twentieth century houses on lower ground towards the Darent. Ground levels, drives and occasional spring water on the clay are the usual causes.

Otford, Kemsing and Seal

Villages below the Downs with flint, brick and timber framed buildings. Breathable repairs and timber assessment are what most surveys come down to.

Damp proofing questions in Sevenoaks

Nearby

• Damp proofing in Swanley
• Damp proofing in Edenbridge
• Damp proofing in Tonbridge
• Damp proofing in Tunbridge Wells

Book a survey before you pay for damp proofing

An independent survey before you pay for damp proofing in Sevenoaks. Fixed fee, same day reply, written report within 24 hours.

Book a Survey or call 07386 225526