Looking for the Best Residential and Commercial Roofing Company in Jamestown
We believe that a roof is the most integral part of a home. It’s what holds your walls together and keeps your house, your possessions, and your family safe and secure.
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Wind pressure is a common cause of failure for tiled roofs. As the wind moves over the roof it produces upward forces causing the roofing tiles to rattle or be removed completely.
Contrary to common belief, roofing tiles are not "blown off" a roof. The wind creates an upward force as it travels over the roof, causing the tiles to be sucked upwards. It is important to understand this subtle distinction in order to build a more secure roofing system. Securing tiles against upward lift is the key to keeping the tiles on the roof.
As the wind travels over the roof area, it causes the air pressure on top of the roofing to decrease. At the same time the pressure underneath the roof increases. The increase in pressure inside the loft space results in a positive pressure on the roof tiles. The negative pressure above causes the tiles to be sucked upwards, lifting the tail of the tile. The lower the pitch of the roofing, the higher the forces will be.
If the tiles are being sucked upwards rather than blown, the old method of roof tile fixing may not be the best. Traditionally roof tiles are nailed or pegged at the head or top of the tile. This secures the tile against the force of gravity but has little effect on upward tile lift. In fact the only thing securing the bottom of the tile is the tiles own weight.
Tests in the United Kingdom have proved that a roofing tile clipped or secured at the bottom can withstand 5 times the force of a head nailed roof tile. Tiles can be clipped or wired to ensure the tail is secured against wind uplift. This also stops the annoying rattle or chatter sometimes associated with wind swept roofs. The chatter occurs as tiles are lifted and dropped by the wind vortex. I prefer to use a bead of silicone between the tile courses to act as a second line of defence against tile chatter.
It is important to note here that modern roofing tile clips must be installed correctly if they are to have any effect. Tile clips are usually nailed in close proximity to the interlocking channel. Because of the risk of damaging the tile, there is a tendency to move the nail too far away from the interlock. The clip must be positioned at right angles close to the tile. The roofing clip should be securely bedded to prevent the tile working loose. In my opinion, the old system of wiring the bottom of the tiles is superior to modern clipping. The wire fixes to an eyelet on the bottom of the tile and in between tile courses onto the supporting baton. This has the effect of clamping down the tile. I have re-roofed wired roofs that are over 50 years old and the wire is still clamped tight.
The most important roofing component when it comes to preventing wind damage is the roofing felt. Roofing felt or sarking is placed under the batons before the tiles are fixed. The primary function of all roofing felt is to prevent wind damage. The waterproofing of the paper is far less important than its ability as a wind barrier. The sarking prevents the increase in pressure inside the loft, thus preventing wind uplift. It must be fixed securely with 150mm overlaps. An extra baton should be placed at the point where the sheets overlap to prevent wind travelling between sheets. If the felt is not correctly secured the wind force will be focused on the weak spot causing more problems.
All ridge and hip tiles need to be mechanically fixed in areas prone to high winds. Roofing mortar alone should not be relied upon to hold these tiles secure. Once the bond between tile and mortar is broken the tile can work loose. They should be nailed, clipped or wired.
The areas most lightly to be submitted to wind uplift are the eaves, verges and ridges. In these areas it is prudent to take extra precautions with your tile fixing. Nail and clip all tiles around the periphery.
A little extra time taken at the installation stage will ensure the roofing tiles stay secure in heavy weather. The extra cost is outweighed by the savings in maintenance and piece of mind.
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Corrugated Iron Roofing is durable, lightweight and easy to install. If a few extra precautions are taken with handling and fixing, the finished product will greatly be improved.
Over half of the mistakes made while constructing a corrugated iron roof can be traced back to incorrect storage or handling. The iron has to be handled and stored correctly because the surface is very easily damaged.
Leave the metal roofing at the manufacturers until you are ready to start installing it. Aim for delivery the day before roofing starts. If the roofing iron arrives before you are able to fix it, you must ensure it is kept bone dry. It is a common mistake to assume that because they are roofing sheets, they can withstand moisture. If the roofing sheets are stacked together and they get wet, they will stain. White rust forms on the coating and it is very difficult to remove. If your roof sheets do get wet, separate each individual sheet. Use bearers to allow airflow around the metal. This will prevent the corrosion.
Gently does it
As for handling, care needs to be taken in order not to damage the paintwork. Sliding sheets across one another will damage them. When separating the roofing sheets, you should lift them cleanly upwards without scratching the one underneath.
Spend more money
Installing a roof can be time consuming and costly. The last thing you need is to have to keep spending money on maintenance. If you scrimp on the cost of fasteners you will forever be replacing loose nails and fixing leaks. Choose good quality roofing screws. These will provide a more secure fixing and last as long as the roofing iron. It's important not to over tighten the screws. Just tight enough to lightly compress the neoprene washer is sufficient.
If you pre-drill the holes for your roofing screws on the ground, it will be safer and give the roofing a neater appearance. This is only possible if the purlins run parallel to the eaves and the roof is reasonably square.
Using a quality drill bit makes the job easier. The drill bit should be slightly larger than the diameter of the roofing screws. This will prevent stress fractures as the sheets expand and contract.
Take accurate measurements of the purlin centres from the eaves and mark the roofing sheets ready for drilling the screw holes. Don't forget to add the drop into the gutter to your measurements, usually about 50mm. It's better to use chalk for marking corrugated roofing iron because pencil may damage the surface.
Cut to the quick
Cutting corrugated iron roofing sheets with a disc cutter makes the job easier and faster. Unfortunately, it also damages the roofing iron beyond repair. Hot particles of steel imbed themselves into the surrounding metal allowing it to corrode. Nibblers will do the job adequately as long as you are careful with the swarf. It's preferable to cut the sheet with hand shears or best of all power shears. A better finish can be achieved if you make two cuts. The first cut 50mm away from your finished edge allowing you to neatly trim to the line with your second cut.
If you find scratches on your roofing during installation resist the urge to paint it. The paint may well look like a good match from the tin, but after a couple of seasons weathering the patched paintwork will stick out like a sore thumb. Contact the manufacturer and ask for advice on making repairs to their product.
Laying the roofing
Before you start laying the roofing sheets check that the roof is square. If the roof is not square you can still achieve a good finish if you even out the difference, between the two barges. The difference will then be less noticeable as it will be covered by the barge flashing. Run a string line along the eaves, 50mm into the gutter and it will provide you with a straight edge for the roofing sheets.
On completion it's important to clear the roof of any loose swarf. Tiny particles of iron left on the roof will rust and ruin the surface. A soft brush will do the job or ideally a leaf blower can be used.
A well installed corrugated iron roof will give years of maintenance free service. If you take a little extra care with the preparation and fixing, you will achieve a superior finish.
Roofing is one of the most important investments you can make. Improper, aged or substandard roofing can lead to a host of other more expensive problems. If you are selling your property, a well-chosen roof can yield a solid return on your investment. Whatever your budget or design desires, whether you want architectural shingles, tile roof installation or something in between, a Roof Master consultant will work with you to make it a reality.
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