Easy to retrofit roof
AFTER ASSESSING THE DAMAGE caused to buildings from Category 5 Hurricanes Irma and Maria, witnessing the heart-breaking misery of those who have lost so much, observing unrestrained looting of non-food items, and experiencing the halt to all national economic activity, I have returned to Barbados more convinced that we can avoid the foreseen national misery if we choose to.
The prevailing defeatist attitude claims that homeowners can do nothing about foreseen threats. This explains the general absence of initiative to improve the resilience of our houses, which should be our primary shelters during natural hazards.
I bring good news. For despite the catastrophic building failures and the significant number of roofs damaged, there were many roofs that survived intact. These buildings had several common features that can result in economical building improvements for all Caribbean residents.
If your roof comprises metal cladding on a supporting timber frame, then your roof is likely vulnerable to extensive wind damage. Fortunately, you can simply strengthen your roof yourself, or you can get a carpenter to do it for you. I have calculated the following costs for the three-bedroom, two-bathroom house with a hipped roof shape that is shown in the 1993 edition of the Barbados National Building Code.
The wind will try to remove the metal cladding first. This cladding should be 0.5 mm thick to reduce the likelihood of it tearing. The roofs that survived Category 5 hurricanes had screws that were spaced at 75 mm (3”) at the eaves and ridges, and 150 mm (6”) elsewhere.
Approximately 720 additional screws are needed, and each screw cost about 35 cents, resulting in a total building materials cost of about $250. A carpenter should be capable of installing the additional screws in less than one day for around $150.
If the cladding is secured to plywood T1-11 boards, then the boards can be secured to the rafters with longer screws at the rafter locations. Each longer screw cost about 55 cents each.
With the roof cladding and boards secured to the rafters, the wind will try to separate the rafters. The rafters can be secured with BRC rafter connectors. Approximately 80 rafter connectors are required, which cost about $1.21 each, resulting in a total materials cost of about $190, including screws. A carpenter should be capable of installing the connectors in less than one day for about $150.
The remaining roof connection is at the rafter/wall junctions, which can be reinforced with rafter/purlin connectors. Around 120 connectors are required, which cost about 94 cents each, resulting in a total materials cost of about $230, including screws. In masonry walls, concrete screws can be used for an additional $90. A carpenter should be capable of installing the connectors in less than one day for around $150.
The total materials cost of securing your roof is in the order of about $820.
Homeowners do not need to do all of this work at once. They can start with the metal cladding and work their way down. Most of the work is simple enough that families can do it themselves. Of course, there are other options.
The cost to replace the roof after the hurricane is about $40 000. Home insurance annual payments normally exceed $1 000 and the homeowner will be required to pay the initial approximately $750 of any damage.
A customer-focused home insurance company can consider allowing one annual premium to go towards roof strengthening. A caring Government can consider removing all taxes from hurricane connectors and screws, resulting in a price reduction of about 30 per cent. The Minister of Finance has another opportunity to show that he cares.