Posts Tagged ‘deck’

Deck hunting season is open!

The MacLennan staff are starting to emerge from the basements, blinking in the sunlight and preparing to work on decks. Winter work on basement decks is at best difficult and at worst, carried out incorrectly in poor conditions.

Sprayed and hand applied liquid Waterproof systems should never be applied on damp decks. They should never be applied when the ambient temperature is not at least 3 degrees above the dew point, even if the sun is out. We rely on bond to resist outgassing.

This applies to most forms of waterproofing on decks and around basements. Even the sheet membranes normally have a primer which relies on the dry warm conditions for installation.

Planning a basement.

If you are planning a basement you should be sequencing the work so as the critical deck and external waterproofing is carried out in the spring, summer and early Autumn.

If the work has to be carried out in the winter then you have to cost in Winter primers, tenting, frost blankets, installing and removing covers, drying of surfaces and downtime when work just cannot happen unless fully tented and heated.

All of this preparation is very rarely considered even when set out in supporting information and data sheets supplied by contractors and manufacturers.

This is all critical.

If you allow or worse force the work to happen in inappropriate weather and environmental conditions you will have failures.You cannot apply waterproofing the day after rain, you need at least a good days drying after the water has been cleared off of the deck.

Winter Deck & Roof Waterproofing Problems

Like all waterproofing and roofing contractors MacLennan have a tough time trying to apply waterproofing systems in Winter conditions.

Note to contractors, clients and project managers. If you are planning a roof or deck then do it in the spring / summer and hope it doesn’t rain.

All waterproofing and flat roofing systems require reasonable weather.

A responsible contractor will not even attempt to install if the temperature is below 5 degrees or if it is not 3 degrees above dew point. Relationships may be strained by a lack of progress on site, and then on the first day of reasonable weather every project manager will expect that they are next on the list for attendance, when in all likelihood a good busy contractor, will have a number of delayed projects and all for important , demanding clients who are desperate to complete their work and get there building dry. This is a problem shared by the whole industry, which leads to bigger problems when waterproofing contractors carry out installations in inclement conditions to keep the client happy, and then have a failure / leak as a result.

If you must programme work for Winter months remember the cost of a leak will be far more than the cost of a delay.


The golden rules are that work must not proceed unless :

  • Temperature 5 and rising Temperature 3 above dew point, no damp on surfaces.
  • Generally it is not possible to apply adhesives, primers, coatings for at least 24 hours after rain. It can appear dry and sunny but the dew point can still be very high in conditions of high relative humidity.

Remember if the contractor is not installing he is not earning, so he is just as motivated as you are.

MacLennan do have cement based systems for wet decks but not cold and Polyurethane systems for application when quite cold but not wet. Nobody has a system for cold and wet decks.

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