10 Oct 2020

Damp walls & Driving Rain

Damp walls & Driving Rain

One of the most common damp problems afflicting buildings in the UK is rain-driven moisture soaking through porous stone, bricks or mortar.  This is especially so during pronlonged periods of wet weather such as Scotland and Northern Ireland have endured in recent months.  

The heavy rain mimics constant immersion, saturating soft masonry especially old pointing, sandstone, limestone and clay bricks which can absorb water like a sponge. 

Initially this saturation is confined to the external surface of the building but over the years water gradually forges its way ever deeper into the walls until finally it shows up on the inside as damp patches on the internal plaster finish.   This dampness ruins the decorative finishes and often promotes mould growth and other more serious fungal infestations of the structural timbers.

However, it is often much easier to rectify than people think by simply applying a premium grade water repellent such as our "Extreme Climate".  In fact this is one of the rare occasions in life when the cheapest solution is often the best!!

Here are some of the many frequently asked questions....

1.  Is water seal breathable?

Yes, Kingfisher "Extreme Climate" is 100% microporous.

2.  Is it easy to use?

Yes, "Extreme Climate" water seal can be applied over small areas (less than 50 sq m) by brush or over larger areas with a hand pump solvent resistant sprayer.

3.  How long will it last?

Typically it will hold back lateral penetrating damp for 10 years.

4.  Will it trap moisture in my stone or brickwork?

No, it uses similar fluoropolymer technology to that found in modern waterproof jackets so it repels water droplets whilst allowing the much smaller water vapour molecules to evaporate freely.

5.  My property is a listed building, will building control permit me to use a water seal?

As long as you can demonstrate that the product is 100% microporous by referencing the data sheet for "Extreme Climate" (on our website), there should be no objection to using the product.  BCOs and architects should be aware that products based on fluoropolymer, polyoxo aluminium stearate or siloxane chemistry are ALL fully vapour permeable.  Kingfisher manufactures all types, please ring for project specific advice. 

6.   Is "Extreme Climate" water seal compatible with lime mortar?

Yes, it offers excellent performance on walls pointed with lime mortar.

7.  We have just re-pointed using lime mortar , why is damp still coming in during heavy rain?

We have lost count of the number of customers who have undertaken expensive re-pointing with lime mortar in an effort to stop penetrating damp only to find that such work has provided little or no improvement.  Lime mortar is an admirable material with deisirable qualities of vapour permeabilty and flexibility, especially in hstoric buildings but in our experience its water resilience in punishing conditions is often lacking.  Apply "Extreme Climate" water seal to enjoy the benefits of lime pointing wihtout the headache of penetrating damp.  (Allow the mortar to cure for at least 14 days before application).

8.  Will water seal bridge cracks in the masonry?

"Yes" and "No".  Yes it will usually repel moisture from ingressing through hairline cracks (less than 0.5mm) but any wider cracks should first be repaired by re-pointing or other conventional methods.

9.  I can see where damp appears inside my property but there is no obvious defect visible outside, how do I know where to treat?

The honest answer is that if the problem persists after reapairing obvious cracks and re-sealing window frames etc, it can be very difficult to pinpoint precise problem areas.  Even experienced surveryors and structural waterproofing professionals can't always predict the path of moisture in a wall becasue there are so many variables (voids in random stone, bridged ties in cavity walls, weak mortar mix, porous stone etc..).   However given that the material cost to treat a typical 50 sq m elevation is likely to be under £135 it is often not worth engaging in expensive or destructive surveys until you have tried "Extreme Climate" water seal first.   If the problem persists you will at least know that porous masonry is not the problem and you can explore rising damp, leaky roofs or defective pipework as potential sources.

10.  The description says it is a "one coat application", can I apply additional coats if I wish to?

Once cured the fluoropolymer in "Extreme Climate" water seal does not bond well to itself, so unless the surface is very exceptionally porous (some sandstone, very old clay bricks and artificial stone) we do not recommend additional coats.

Hopefully you will find this snapshot of questions useful but you are welcome to contact us for further guidance on any of the issues discussed above either by calling us on 01229 869 100 or via the enquiry form on our website.

View Extreme Climate here.

Extreme Climate - Next Generation  Water Seal