Careful how you load the attic

TWO weeks ago, I was talking about roof underlays or the lack thereof, and how this was possibly the cause of a ceiling collapse. Sue picked up on this and is now a little worried.

I was shocked to read the information in this week’s Handy Mac. We have a small house in Fish Hoek built about 40 years ago by a reputable construction company and it was the first cluster development in Fish Hoek. Our opinion is that these houses were well built. However, we do store stuff in the roof space and have noticed that, over the years, the yellow plastic underlay has become very tatty. There have been no roof leaks so we have not worried about this. You say the underlay is to stop wind uplift in the roof. To replace this yellow underlay, it seems we would have to remove and replace the plastic underlay beneath the tiles. This is a huge job. Is that what you are recommending?

I replied to Sue as follows:

I am not trying to cause panic, and it will not happen in every case. I have the same situation at home and have had no trouble for years. The trouble develops when the roof starts to sag, joints open and more and more wind gets in. It is likely to lift the tiles before doing damage to the ceiling. The one I saw and referred to also had a lot of bad building. So, I would not do anything for now. Just check that your roof still looks straight and level.

However, you say you store stuff up in the roof. Did you build a platform and is the weight distributed evenly?

This scenario raises many points for discussion. First, what is the best underlay to put under your roof covering? This is a subject which could fill a column for weeks, and the answer really depends on what you are trying to achieve. As with most things in life, trying to achieve cost savings has meant designs have changed and with the changes have come “problems”. Clay tiles were fixed on steeply sloping roofs without an underlay, as were mazista slates.

The steep pitch ensured water ran off quickly and limited uplift. Houses were so well built that the top of the ceiling could be covered with clay as an insulation and walls were thick enough to keep out heat.

Fast forward to today, and the lower the pitch, the less timber, the cheaper the roof, and clay tiles and mazista coverings have priced themselves out of the market. So, we are left with trying to find cheaper alternatives that work, and the best way to insulate.

I will go into more detail in the coming weeks.

Roof coverings have changed over the years. PICTURE: DAN GOLD