Roofing hold-downs resist uplift

Roofing hold-downs resist uplift

Here’s a simple way to help prevent metal roofing from being blown away. Roofs are typically quite vulnerable to uplift in windy areas. There are commercially available roof hold-downs that bolt trusses and rafters to walls, but I’ve never seen the system described here. It was inspired by hearing all the stories about metal roofing blowing off in Haiti. (Apparently it’s routine to reattach metal roofing after major wind storms.)

This hold-down system is low cost and simple. It consists of 1/4″ x 3/4” flat galvanized steel bars bolted to purlins. Drill bolt holes at the top of corrugations. Use rubber washers to prevent roof leaks. (Insert rubber washers below the bars.) The drawing shows hold-downs located at the top, bottom and middle of each 8’ long sheet of roofing. Adjust the spacing between hold-downs for your region. The higher the wind speeds, the closer the spacing.


Comments

Roofing Hold-downs — 5 Comments

  1. thanks Owen, it’s apparently a thermal pool cover for a kidney shaped swimming, so I think it would suit using it for a green roof…I don’t know what you mean by 6 mil poly…

    • Yes, it sounds like it will work.

      6 mil poly is also called 6 mil plastic sheeting. It’s available in rolls from virtually every building supply center.

      This discussion has sparked an upcoming blog post. Thanks for contributing.

  2. When covering the roof with something waterproof, could you use pool covering or does it need to be pool lining?

    • I assume you’re talking about making a living roof (green roof). I think a number of materials are possible. Not sure what pool covers are made of. But [recycled?] trucker tarps could work, possibly with added 6 mil poly below. Rubber pond liner is the most waterproof and durable material, but as you know it’s expensive and is made from nasty chemicals. For my dome, I used 2-1/2 layers of 6 mil poly and have had no leaks so far. (The half layer is a small piece on the very top.) You need to cover 6 mil poly carefully to avoid punctures. Some use old carpet or cardboard while adding soil against it. Maybe screen out rocks before adding soil.

      Edit: I just checked some pool covers and believe they will work if they’re in good condition.

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