One solution to reduce the vulnerability of your house is to have your foreman properly trained. I now offer a training course that will lead to participants receiving the Diploma of Walbrent College. See article on Walbrent College for further details.
I have come to the unfortunate realization that we are doomed to experience the misery and economic setback that other Caribbean islands experienced after being examined by major hurricanes. These countries only paid attention to building standards after their buildings were weighed in the balance and found wanting.
I have given up hope that the Town Planning department will accept their responsibility to ensure that houses are both designed and built properly, until they actually see the devastation that they could have prevented. I have also given up hope that the Ministry of Housing will accept its responsibility to ensure that their proposed 2,500 “units” will be anything but sub-standard.
During the past 12 years, I have rarely seen a house built that confirms to the minimum structural requirements of our national building standard. It is very distressing to report that every one of those sub-standard houses could have been built properly at no additional cost. There seems to be a strange belief among builders and homeowners that they can somehow realize good quality construction by simply wishing it to be so.
How did we get to this sorry state? The start of this current building boom saw inexperienced persons offering themselves as building contractors. This was a well known practise, and therefore it was critical that building standards be effectively enforced. Fortuitously, the Barbados National Building Code had been published approximately 2 years prior; however, for some inexplicable reason, the inexperienced builders were not required to comply with these minimum building standards. A timely opportunity was therefore squandered as the relevant authorities refused to accept advice continually offered during the past 12 years.
I have decided to no longer publish articles on the substandard building practises in Barbados. If there is a single builder in Barbados building structurally safe houses, then please contact me and I would happily publish the construction photos and promote your business free of cost.
I will use this final article on substandard building to inform home owners of what to look for and what to do if they find it. Most of the photos were taken within the past week.
This is a good start. Found the building on solid rock.
Notice the layer of topsoil at the surface. This will compress, therefore do not allow your builder to build upon it. If he insists, then dismiss him. The underlying layer is a mixture of predominantly clay and gravel sized soil. The clay will compress, but it might also swell if it gets wet. To avoid the risk of the building settling or rising, you should found the building on the rock. If you do not believe me, then believe the Great Master Jesus who noted that wise men build their houses on rock if they wish them to survive natural hazards. I believe that He indicated that you are just short of an idiot if you allow your builder to do otherwise and expect the same result.
The builder has excavated to rock, then placed fill on the rock and compacted only the top layer. The builder will try to justify doing this by stating that it will give him a relatively flat surface upon which to build. However it is in violation of the building code and introduces the unnecessary risk of uneven settlement. If he does not found your house upon the rock in accordance with Jesus’ advice, then dismiss him and find a builder who believes.
You should have your builder drill down at least 3 m (10′) to ensure that you are not on a cap rock or over a void. Remember, we do live on a predominantly limestone island.
The thickness of the footing should be at least 200 mm (8″) for a single storey house and 250 mm (10″) for a two-storey house. Here we have 150 mm (6″), and below it is 100 mm (4″) which is clearly insufficient. If he does not rebuild this properly at his own cost, then dismiss him. You will save yourself a lot of unnecessary grief.
This concrete was not compacted properly, and a condition known as honeycombing is the typical result. This honeycombing can provide a path for moisture and air to reach the reinforcement and facilitate its corrosion. If he does not correct this at his own cost, then dismiss him and find a responsible builder.
Here, there is insufficient concrete cover protecting the reinforcement so that its corrosion is almost guaranteed. If he does not repair this at his own cost, then dismiss him and find a responsible builder.
Regrettably, this will soon be covered up and the home owner will be unaware that the foundation is sub-standard. Within a few years later, this home owner will be calling for an Engineer to find out why the house is cracking up.
If this is what your builder is doing, then ask him to redo it properly. If he refuses, then dismiss him. Why needlessly put your family at risk during an earthquake or hurricane because of his substandard work.
Partial knowledge is just as ineffective. He filled the block’s cores correctly, but did not include the reinforcing bars.
This is what you want to see.
Here, the builder has only one side of each window opening reinforced. I do not believe that he is intentionally doing work which he knows to be substandard, rather, I believe that he simply lacks the knowledge. That is why the failure to require builders to follow national building standards is such an unnecessary tragedy. BNBC 2.425.5 (b) specifies one 12 mm diameter bar either side of each opening.
This house is likely to be structurally unstable during a hurricane or earthquake. Over 90% of houses built during this building boom are similarly structurally unstable. They are not expected to survive the first major earthquake or hurricane.
I cannot blame the builders for this structurally unsafe practise, for they are simply building what is on the approved plans. The fault lies with the inexperienced architects and draughtspersons who designed the houses, and with the Town Planning Department who should never have approved the sub-standard designs in the first place. Unless your house has been designed by a structural Engineer, it should comply with the specified minimum structural requirements of the Barbados National Building Code (BNBC).
The BNBC (section 2.405.8) specifies that external walls must have shear walls to resist lateral forces from Earthquakes and Hurricanes. These are to be one 3 m (10′) wide wall from foundation to roof level at each face of the house, and it must not contain any window or door openings. If one 3 m wide shear wall is inconvenient to the design, then two 2.0 m (6′-7″) wide ones are permitted. You are welcome to look in vain for such houses built during the current building boom. What is more distressing is that to accomplish this would have cost all of $0.00. You should therefore review your drawings and get the designer to make the necessary corrections with dispatch.
This is where a lot of damage is done. There are basically two types of high tensile steel reinforcement that have been used during this building boom, the British Standard BS 4449 and the American Standard ASTM A615. Since the American steel is 85% cheaper, builders prefer it. However, one cannot simply substitute one type for the other. The British steel is approximately 10% stronger; therefore if you want to use the American standard, you need to use more of it which makes the cost approximately equivalent. In the photo above, the link ends should be bent into the beam.
The structurally unsafe aspect of the American steel is realized when it is bent around radiuses specified for the British steel. The American standard steel needs larger radius bends and tends to fracture when bent around smaller radiuses. This means that the beams and columns will likely be ineffective when they are needed most.
This is how roofs are typically built in Barbados and it complies with the BNBC. However, it is vulnerable to high winds.
This is what happened in Grenada during hurricane Ivan in 2004. I informed the relevant authorities that it was found to be ineffective near the start of this building boom. However, to-date, they have not issued the necessary errata warning persons not to use it. If your builder insists on using this roof connection, then insist on hurricane straps. Ensure that they are made of stainless steel in order to avoid corrosion and their subsequent replacement.
Make sure that the frequency of roof connections are increased at the eaves, gable ends, apex, and hip ridges. They should be at most 150 mm (6″) apart in the shaded areas and at most 300 mm (1′) apart in the clear areas. Finally, do not pay your builder until he has built each stage of your house properly.
Grenville Phillips II
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