Damp

By February 7, 2020April 15th, 2020Managing a Renovation

Patches of damp in your home can be terrifying for homeowners to find. The discovery brings to mind long-term, deep-seated issues that are expensive, intrusive and time-consuming to fix. That’s sometimes the case, but not always, and in all cases the sooner areas of damp are investigated and treated, the better (and the cheaper…)

Here we look at the main causes of damp in your home.

Leaks from above

These are usually the most obvious to diagnose, and caused by e.g:

  • a leaking roof, gutter, rainwater pipe, soil pipe, etc.
  • a leaking bathroom/ kitchen/ radiator above
  • a damaged chimney/ chimneypot
  • damaged brickwork, window surrounds, etc.

Leaks from above can often be fixed easily by finding and eliminating the cause i.e. fixing the underlying problem so the water stays where it ought to be (on the outside of the walls/ roof or within the pipes designed for it to pass through).

Stain caused by water penetration above skirting board in corner of room
Low level damp can have many causes, but as this is a 2nd floor flat a leak is the likely cause
Damp Stain caused by water damage near ceiling of a room
Ceiling level water damage also points to a leak from above

Example – we’re working on a flat which suffered extensive water damage because a rainwater downpipe was blocked by a plastic bottle at roof level (how??). Rain had been pouring down the brickwork for months. Once the bottle was removed, the rain stayed in its pipe and the flat is drying out…

Complications in fixing these issues arise if the source is difficult to access, I.e.:

  • The leak is coming from a bathroom above in a separate apartment.  This repair will require the cooperation of the owner (and any other occupiers) of the apartment above, and how effective the repair is will depend on how well it’s done.  (You don’t normally have control over this, tho most standard leases will require all owners to ensure there are no leaks (of water or anything else) from their properties.)

Example – we’re working on two separate flats suffering leaks from bathrooms above. One neighbour v cooperative; the other not at all – we’re testing our negotiating styles…

  • Problems in accessing the roof/ gutter, etc. if too high for a ladder to be used safely.  This may require scaffolding – which is expensive – so if it’s essential to fit scaffolding, it’s usually cost-effective to take care of any other maintenance in the same area at the same time (i.e. external repairs, redecoration, cabling, etc.)

Penetrating Damp

If the wall of an occupied building sits directly against an area containing water (such as earth…), the wall will eventually show signs of dampness unless a barrier against damp has been properly installed and remains in good condition. This situation usually arises when the room is question is below the adjacent ground level – common in basement flats.

Rising Damp

This is dampness being drawn upwards (usually by capillary action) from the ground – either because of the amount of water occurring naturally in the ground from rainwater or because of excess water cause by a water leak in the ground nearby (i.e. from a mains water pipe (incoming) or a drain pipe leading to the sewer (outgoing).

In both situations, the solution is usually to fit a barrier to prevent the dampness travelling from its source into the area.  This barrier can take a variety of forms and sometimes several methods are used at the same time – these vary in price, effectiveness and level of disruption to the areas in questions.

Wall stripped back and prepared for a damp proof membrane
Preparing for a damp proof membrane
Damp proof membrane in the process of being fitted
Fitting a damp proof membrane

These solutions all tend to be fairly disruptive.  Normally you have to remove any fittings against the wall / floor in question, including built-in furniture, skirtings, electric points, etc. and it’s often wise to lift the floor adjacent to the affected area.

A damp specialist will advise on the best ‘barrier’ system to use – this may be:

  • a waterproof render (plaster layer) applied to affected area and its surroundings,  and/ or
  • a membrane system applied over the same area.

The affected area can then be skim-plastered, redecorated and re-fitted in the usual way.  It’s really important, however, that the ‘barrier’ isn’t damaged (breached) by having fittings attached with screws, or new electric sockets, for example, fitted to the treated area in the future.

Consider having nearby pipework checked for leaks – CCTV surveys of nearby underground drainage can be a good idea in identifying these.

Issues to consider after a leak:

  • allow the affected area to dry thoroughly before attempting to repair – redecorating a damp wall will simply result in the damp patch showing through in future.  A dehumidifier may help in this situation
  • check affected area for signs of mould or rot, and consider treating the affected areas to prevent infestation in future.

If you are considering renovation work, we recommend checking for and resolving any causes of damp as part of the works, to prevent future damage to your lovely new finishes.

We can help with this and all aspects of your renovation – get in touch!

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