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 mind-set is that we cannot avoid such misery. It is expressed in terms like: “what will happen will happen”, and “if the roof is to go, then it will go”. This defeatist attitude that claims that homeowners can do nothing about foreseen threats 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 buildings 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 3-bedroom 2-bathroom house with a hipped roof shape that is shown in the 1993 edition of the Barbados National Building Code, which I will conveniently refer to as the Building Code.
The wind will try to remove the metal cladding first, which should be 0.5 mm thick to reduce the likelihood of it tearing. The Building Code’s minimum standard is to secure the cladding with screws spaced 300 mm (1 ft) apart. However, past experiences with Category 3 and 4 hurricanes has resulted in screws that are spaced 150 mm (6”) apart at the eaves and ridges, and 300 mm (1 ft) apart elsewhere.
The roofs that survived Category 5 hurricanes exceeded this new standard by generally having one screw inserted between the existing screws. Therefore, the spacing was 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 approximately $250. A carpenter should be capable of installing the additional screws in less than one day for approximately $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 approximately $1.21 each, resulting a total materials cost of approximately $190 including screws. A carpenter should be capable of installing the connectors in less than one day for approximately $150.
The remaining roof connection is at the rafter and wall junctions. If truss anchors were not used, then this connection can be reinforced with rafter/purlin connectors. Approximately 120 connectors are required, which cost about 94 cents each, resulting in a total materials cost of approximately $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 approximately $150.
The total materials cost of securing your roof is then in the order of approximately $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 approximately $40,000. If you cannot afford this, then you should either start saving or obtain insurance. If the house is insured, then the annual payments will be over $1,000 and you will be required to pay the initial $750 of any damage.
For both of these options, you would have lost your contents and will have to suffer through the misery of discomfort and reconstruction. Why choose this option when a better alternative of preventative strengthening exists?
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 approximately 30%. The Minister of Finance has another opportunity to show that he cares.
You got your wish.
Grenville was criticized on the talk show yesterday for misleading the public. Something about the homeowner needing to spend money to peal-back the roof to assess if the rafters are pinned with steal to the ring-beam.
I want to thank Grenville for his advice in this column.
However, while it is thoughtful and considerate of him to think of the little man (who probably cannot afford to spend more than a few dollars to make his roof more secure), I would be grateful if he could tell us what needs to be done to make middle class housing secure in a Category 5 storm.
Many Barbadians have the income or accumulated savings to replace metal roofs with concrete slabs. To install high impact windows. To buy shutters, if necessary. How costly would these changes be?
Why pay an insurance company $1,000 a year to insure a house? Put the money in a dedicated savings account. That way, if there is no storm, the money is yours to help finance your retirement.
Barbados is lucky enough to lie south of the main hurricane corridor. Self-insurance is an excellent option, folks.
@chad99999 September 28, 2017 at 8:04 PM “Why pay an insurance company $1,000 a year to insure a house? Put the money in a dedicated savings account. That way, if there is no storm…”
Yes. But what if there is a storm after year one, two, or three and I have only saved one thousand dollars or two or three, and I incur $40,000 of damage?
Will you castigate me as an ignorant, ill disciplined West Indian who cannot or will not save?
Grenville, as a potential leader of Barbados, what are your views on the current C&W matter?
Thanks to BU and Grenville for providing helpful professional information.
There are a lot of houses in Barbados that would be strengthened using Grenville’s suggestions.
A timely piece…a few questions
1) screws….hex head with a neoprene washer?
2) BRC rafter connector…I notice a few types. In retrofit some are obviously disqualified. Any one design preferable (wood structure)
3) Any value in attaching purlins to under side of the rafters?
As an aside, walking around on sloped metal roofs, esp in a 2sty or higher structure, isn’t really for the novice.
GOOD SIMPLE PRACTICAL INFORMATION GIVEN HERE
HOPE IT IS PUT TO USE
I do not know anything about construction and building. I have heard people referred to roofs as Hipped or Principle (not sure if that is spelt right). Is the principle roof that roof that carpenters construct in a v-shape and then install on the top of the house held down by steel? Is the advice given for the Hipp the same for this type of roof as well? Also, what is the best or how much of an angle on the roof is appropriate for hurricane force winds? Besides that good sound information.
This article is a step in the right direction. We should be discussing and, if possible, taking measures that will minimise the damage that may be caused by hurricane, e.g. placing some electricity/telephone lines under the ground; removing trees or tree branches that overhang such lines; improving water drainage; and constructing elevated buildings in flood prone areas.
Dominica, BVI of the islands severely impacted by the hurricanes have an opportunity to rebuild the infrastructure to a higher standard. Barbados and the other countries should be supporting such an approach with a view of learning from the Dominica ‘prototype’.
@ David I support your reasoning. If I were building a house in Barbados it would be cat 5 hurricane resistant.
I would also build the ground floor 4 feet above grade and the only fruit trees on the property would be citrus, sour sop, cherry ,mango and banana.
We need to keep this “conversation” going on BU and hopefully one of you may benefit.
I have no faith in government implementing and ENFORCING building codes or maintaining rods, drains and watercourses.
Kudos to you Grenville for doing the analysis and sharing the findings.
Continue using your engineering skills, experience and expertise to improve the infrastructure and lives of others in the Caribbean, We absolutely need it. Stay away from the politics.
@ David, Is there an online copy of the 1993 edition of the Barbados National Building Code ?
It is not online.
The reason why certain roofs survived hurricane Irma without damage
PHILIPSBURG — Today photo journalist took a series of photographs of buildings whose roofs have withstood the category 6 storm force winds of Hurricane Irma without much of a scratch. You can view these photographs below and see for yourself.
This is a bit off topic as it doesn’t deal with roofing, but it is another aspect of our infrastructure that apparently needs some reinforcement in order to resist the stronger hurricanes that are predicted to occur in the coming years.
After the hour or so of admittedly very heavy rain earlier this morning (Saturday), I noticed when I stopped in at Massy Rendezvous at around 7pm the same evening there was a noticeable malodorous smell wafting through the night air in the South side parking lot. On leaving Massy and turning right to proceed to the lights at Hwy 7, I noticed the smell of sewage was even stronger as I drove past the FCIB building on the South side of Massy.
So if an hours worth of a tropical downpour overloads the sewers (which are theoretically not supposed to carry storm water run off), what is a hurricane sized rain storm going to do to it?
According to John this is the swamp water smell and not sewerage.
This is Hurricane Irma through a time lapse as it passed over the BVI.
According to John this is the swamp water smell and not sewerage.
While I admit have no qualifications in swampology or even a relevant science like biology, I am still wondering if that is really the case. When Mr. Allard’s GHS nature sanctuary was open to the public I walked through it on several occasions with visiting friends from overseas and never smelt anything like the smell in the air by Massy Saturday night. Also, a few years ago I went on a couple of occasions behind the houses and businesses lining Hwy 7 (just to the East of the Worthing Police Stn & St. Lawrence Gap entrance) until I was standing right on the southern edge of the swamp and walked along the bank for a couple hundred yards and at the time smelt nothing coming out of the nearby swamp like the unpleasant smell lingering in the air Saturday night around Rendezvous/Hwy 7.
I had relatives and friends living in the area when I was growing up in the 60s and 70s before the sewage line went in and spent a lot of time during school holidays in the vicinity of Rendezvous/Hwy 7 and never experienced any “swamp gas” type of smells or recollect hearing anyone complaining about bad smells from the swamp after heavy rains in those days.
Commensense is starting to prevail and all it took was massive destruction.
“CONVERTING FROM TIMBER AND GALVANISE TO CONCRETE ROOFS POST HURRICANE MARIA #HurricaneMaria Jaydee’s Engineering Services
Most homeowners, whom Maria left without a roof over their heads, are now contemplating constructing reinforced concrete roofs for their dwelling homes.
Before this can be done, there are many factors that must be taken into consideration. Concrete roofs require more support than timber roofs. Most homes, which sported timber roofs, might not have the structural frame needed to support a concrete slab.
In some instances, some of the columns do not extend to the ring beam where the roof was attached. In others, the columns (for example stiffeners) present might not be adequate to transfer the load of the slab to the foundation.
The foundation too, might not have been designed to accommodate the additional loading of a concrete slab. It is therefore advised to engage a structural engineer to:
1.Assess the feasibility of rehabilitating a home to include a concrete roof.
Recommend and design what structural adjustments are needed to support the roof.
Design the concrete slab to include provision for waterproofing and anti-crack.
In extreme cases where the structural elements within the building frame are inadequate, exterior foundation pads and columns need to be designed and constructed.
Traditionally, concrete roofs have been constructed flat without any slope which encourages water ponding. It is paramount therefore to ensure that the roof is cast with at least a 1% gradient to allow drainage from the roof surface.
Concrete roofs need not be boring. At an extra cost, they can be cast into gable or hip shaped roofs.
After all this is done, having a good design means nothing if professional supervision is not sought during construction. The engineer can also be charged with taking concrete samples during pours to test, to ensure that the homeowner receives the grade of concrete purchased.”