Archive for February, 2019

maclennan team working

Winter Deck Waterproofing

We are in the middle of a season where main contractors and clients are insisting on deck waterproofing. You should not be waterproofing a deck in the Winter unless you are able to give a contractor 14 days notice of dry weather with a moderate temperature of 5c and rising.

Clearly, this is not possible.

If you do not follow the manufacturer guidelines the waterproofing will fail and the cost of remediation will make the cost of a delayed programme pale into insignificance.

MacLennan also has hand applied systems that we install under our 10-year guarantee, we offer more than other waterproofing and roofing contractors.

before and after adequate surface preparation

Image 1 - This shows a before and after of adequate surface preparation, ground down and free of dust and laitance. 

lumpy concrete surface

Image 2 - This shows bad preparation. A lumpy, laitance filled concrete surface will be at risk of poor adhesion. Proper preparation is essential.

removing existing waterproofing

Image 3 - Waterproofing being removed from a surface that was ground, jet washed and vacuumed. The point being that good preparation is difficult to achieve. In cold wet conditions it is impossible.

damage to cold decks

Image 4 - This shows a failure of work carried out in Winter months. Wet, cold decks make a poor surface substrate.

water damage to decks
deck conditions maclennan have dealt with

Images 5 & 6 -  Deck conditions MacLennan have been called in to waterproof in winter months.

We always advise our clients that Deck waterproofing work with any material or system must happen in the spring and summer.

They often disregard that and try and make the weather the waterproofing contractors problem.. The following rules apply winter or summer but will be even more critical in the Winter.

All surfaces must be correctly prepared. Preparation has to be grinding or scabbling and then either jet washing or vacuuming away of the ingrained dust. Removing the dust is one of the most critical elements of preparation and may require jet washing to remove ingrained dust.

It is critical that all laitance is removed and the resulting surface is sound and dust free.

Primed & Ready

Surfaces are primed in summer to prevent outgassing and aid bond. Surfaces are primed in Winter to provide a sound dry surface and aid bond.

Most Primers do not work in cold conditions or on damp surfaces. There are primers available that are less temperature sensitive and can go on a touch dry surface but they are far more expensive and still limited by site conditions..

You cannot prime a wet surface. You cannot prime a freezing surface even with special primers. This will lead to an expensive failure.

Covering up?

Covering a deck with a tarpaulin is doomed to fail. In all likelihood when you remove the tarpaulin you will spill the water onto the deck. You must use tenting and heating so as work can be carried out under it.

Contractors are always pressurizing waterproofing sub contractors to attend site when the site is clearly not ready. This serves no purpose. You cannot apply waterproof membranes to damp substrates or in cold conditions. Waterproofing contractors who know what they are doing cannot and will not attend.

The clients team is always well aware of the required environmental conditions. 5 and rising, 3 above dew point, dry ( Blue paper test) Do not use Epoxy primer at below 10c.

On-site pressure

It is site managers who when put under pressure of a time critical programme will try and pressurise the waterproofing company to carry out the work. The ones who know their job know it is wrong but want to be seen to be getting the job done.

This attitude is what leads to the millions of pounds worth of waterproofing failures every year. The job should be done properly in the right conditions.

maclennan team working
maclennan team and van

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