Archive for Damp Walls & Insulation

Can EWI Stop Condensation ?

Trying to solve condensation damp is the second most popular reason, for householders  in solid wall homes, to consider having their outside walls thermally rendered or cladded . The most frequent question we are asked is how can external insulation  possibly cure damp condensation problems when it is adding yet another layer to their wet walls ?

How Exterior Insulation Stops Condensation

Solid wall insulation systems cure condensation by moving the dew point of a wall from the internal plaster surface to the outside of the external insulation boards surface ie the coldest part of the newly clad wall is the outside and not the inner sections.

Condensation – wet patches on the plaster leading to black mould or white “furring” – only occurs as a result of warm moist internal air hitting a cold surface such as when showering and seeing the mirror and windows steam up.

What is happening is that the water vapour in the air condenses from a gas to liquid  when it comes into contact with a surface whose temperature has dropped low enough to reach the “dew point ” . This is the point at which condensation thrives and the only real way to stop it is to increase the wall temperature sufficiently to allow the moisture to pass through the walls as vapour and escape to the outside.

What about Interstitial Sweating ?

This is when moisture becomes trapped in the inner core of the wall and cannot escape to the outside as quickly as it needs to and so builds up to a point where the vapour condenses to liquid and begins to wet the core of the wall. Unlike surface condensation this interstitial damp cannot be seen so is especially dangerous and harmfulto the structure of our homes.

All reputable  outside cladding and rendering systems have been tested by the Government funded British Board of Agrement for suitability of use on the UK’s solid wall homes and as part of the thorough testing regime they are checked to ensure they breathe more than sufficiently to avoid trapping moisture in the wall behind the thermal boards.

Better than Standard

The system renders that THINC Wethertex use al perform far in excess of the British Test Standard. The testing authorities use what they call a Dynamic Sweep Gas test to determine breathability and on their scale a material needs to score 25 or below to not be harmful to a home’s structure. Our thermal renders measured 12.8 which is classed as being highly breathable for a cladding system and way in excess of minium standards.

Stop Condensation Now 0800 975 5231 or Email your query

Posted in: Damp Walls & Insulation, Outside Insulation

Leave a Comment (0) →

Damp Walls & Exterior Insulation

When it comes to dealing with dampness  in solid wall homes an investigation should first be made into the underlying cause. If the root cause is either penetrating dampness through porous wall surfaces or condensation damp then an external thermal cladding can be used to clear the problem with the below caveats . If the problem is rising damp then a Damp Proof Injection Course will be needed before any exterior cladding is applied.

Breathable External Insulation

Once the reason for the damp in the walls has been identified then if exterior insulation is appropriate the trick is to use a water vapour permeable insulation board and in this case either a mineral wool or phenolic board is most suited with an EPS polystyrene board being discounted.

Having removed any wet render or paint from the wall and allowed the walls to dry out for a short period the insulation cladding can be affixed without fear of trapping any moisture in the walls.

The insulation and the render coating are both microporous so will stop any more water penetrating into the underlying wall whilst allowing the dampness within the wall to escape naturally to the outside.

If the walls are cavity built and there is a pentrating damp problem then a specialist  wall tie inspection firm should be called in to insert cameras into the cavity and see why the water is tracking across the cavity. This should be done before spending your hard earned money on external wall coating systems to solve what could be a structural problem.

Posted in: Damp Walls & Insulation

Leave a Comment (0) →