Damp proofing in Tonbridge? Get an independent survey first

Why the survey comes before damp proofing in Tonbridge

Most of the walls we are asked to look at in Tonbridge after a damp proofing quote do not need a new damp proof course. They need the water dealt with at its source: a path lowered, a gutter cleared, Wealden brick and sandstone repointed in the right mortar, or a fan that actually extracts. Injecting a wall that is wet for another reason costs real money and fixes nothing, and the tide mark returns once the new plaster dries out.

The quotes we see most often in Tonbridge are injection across the front of a bay fronted terrace and tanking in houses near the river. A bay that leaks at its roof or sill wets the wall below regardless of any injection. Near the river, groundwater beneath a floor is not something an injected course can stop.

The kinds of damp proofing, and what each one is for

"Damp proofing" covers several different jobs. A chemical damp proof course is a cream or fluid injected into a mortar course to stop moisture rising from the ground. A physical course is a membrane or slate cut into the wall, slower and more disruptive. Tanking is a waterproof coating or render that holds water back on a wall below ground. A drained membrane lets water reach the wall and carries it away to a channel and pump.

Each answers one fault. None of them fixes rain coming through Wealden brick and sandstone or brick, a gutter overflowing down a corner, or condensation on a cold wall, and those three account for most of the damp we are asked about in Tonbridge. Replastering is often sold alongside, and on old solid walls the choice of plaster matters as much as anything injected.

Tonbridge walls, and what they actually need

Tonbridge's Victorian houses have solid brick walls with slate courses that usually still work, ventilated timber floors that need their airbricks open, and bays that need their roofs and sills maintained. The Wealden cottages need breathable finishes and sound tile hanging. The post war houses need ventilation and clear courses.

The Medway runs through Tonbridge in several channels across a wide, flat flood plain of alluvium and gravels over Weald clay. The flood storage area at Leigh reduces the risk, but the low ground around the river and the Botany area remains wet, with a high water table in winter. To the north the ground rises onto sandstone and clay, where gardens on slopes can direct surface water towards houses.

• Repairing bay roofs, leadwork and sills before any internal work
• Reopening and adding airbricks to ventilate suspended timber floors
• Fixing leaking flat roof junctions and cavity trays at extensions
• Floor and drainage measures for groundwater near the river, not wall injection

Suspended floors and airbricks in Victorian Tonbridge

Most Victorian houses south of the river have suspended timber ground floors, ventilated through airbricks in the front and rear walls. Over the years, paths, patios, extensions and rendered plinths have blocked many of those airbricks, and in some houses the void now has almost no air movement at all.

A poorly ventilated void stays damp, and the joist ends and wall plates resting on the walls start to decay. The floor smells musty, and damp shows at the base of the walls. Firms then quote to inject the walls and treat the timber. The better repair is usually to restore ventilation, by reopening and adding airbricks and fitting periscope vents where ground has risen, and to replace any decayed timber with sound timber isolated from the wall.

Damp proofing done properly, in the right order

• Find the cause: measure, look outside, rule the alternatives in or out
• Fix the cheap external faults first and give the wall time to respond
• Only then, if a Wealden brick and sandstone or brick wall is still wet at low level with no working course, consider a new damp proof course
• Replaster with materials that suit the wall: lime on old solid walls, never cement on soft brick or stone
• Ventilate and heat so the wall can dry, and check it again after a season
• Keep the paperwork: diagnosis, specification, guarantee and the readings after

How to avoid being oversold

• Never sign on the day of a free survey. A genuine problem will still be there next week
• Ask what else could cause the readings, and how each alternative was ruled out
• Ask for the readings in writing, with where they were taken
• Be wary of whole house treatment for damp found on one wall
• Be wary of tanking or a membrane on an above ground wall that is wet from outside
• Get an independent survey on any Tonbridge job above a few hundred pounds; it often costs less than the plaster you would lose

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 Tonbridge we find that pattern on a minority of the walls we are asked about.

Damp proofing is priced per metre of wall plus replastering, and on an older Tonbridge house that adds up quickly. The survey is a fixed fee, published on our prices page, and its job is to make sure you only pay a contractor for the metres that need it, if any.

Tonbridge is a popular town for families, and buyers often find a homebuyer report recommending a damp or timber specialist on Victorian houses. Most of what is flagged is maintenance: bays, gutters, airbricks. Near the river, it is worth understanding groundwater and flood risk as well. An independent survey before exchange separates fixable defects from site conditions.

After the survey you have the cause in writing, a list of what needs doing in order, and what does not. If damp proofing is part of it, the report specifies the walls, the height and the finish, so the quotes you collect in Tonbridge are for the same job. If it is not, you have the evidence to say no to the quote you were given.

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

Around Tonbridge

The town centre and riverside

Older buildings, shops with flats above, and streets close to the river. Groundwater, parapets and old gutters are the usual causes, and conservation area status often applies.

South Tonbridge and the Victorian streets

Terraces and villas with bays, rear additions and timber floors. The survey concentrates on bays, airbricks and rear drainage.

North Tonbridge and Hildenborough

Post war estates and later housing, with older cottages towards Hildenborough. Mould and condensation on the estates; breathability and timber on the cottages.

Damp proofing questions in Tonbridge

Nearby

• Damp proofing in Tunbridge Wells
• Damp proofing in Kings Hill
• Damp proofing in West Malling
• Damp proofing in Sevenoaks

Book a survey before you pay for damp proofing

Get the cause in writing before anyone drills a wall. We sell no treatment and cover Tonbridge and the villages around it.

Book a Survey or call 07386 225526