The next thing that needs to be considered is cost. What’s your budget? What types of material will you need and how much? What is roofing labour going to cost? Do you have a bunch of friends you can round up? Should you hire a contractor? Do you have the capacity and knowledge to do the project yourself and be confident the job will be done well? Re-roofing your house is a physically demanding job and requires some specialized equipment to make the job safe and efficient.
What is the complexity of your roof? A simple two-sided single storey bungalow with a sloped pitch of 6:12 (6″ of vertical for every 12″ of horizontal) or less, without valleys and dormers, can be easily done by the do-it-yourself individual. Obviously once you begin to add valleys, extra storeys, dormers and steeper pitches … knowledge, material and equipment needs begin to grow beyond the ability of a weekend do-it-yourselfer.
Purely from a safety standpoint, if your house is steep or multi-storied, I would give you a very stern recommendation to NOT roof your own house. The very act of keeping yourself on the roof in this circumstance requires special equipment and knowledge.
So, you’ve given yourself an inventory of your abilities and you’ve decided to do it yourself. Now you’ll need to develop a material list. For the reason I gave in my previous post, stay away from 3-tab shingles to cover your roof area. Use architectural laminate or composite shingles. A bundle of asphalt shingles will cover about 32.3 square feet of roof area. In the roofing industry we refer to the term ‘squares’ as a unit of area that measures 100 (10’x10′) square feet. Three bundles of asphalt shingles will cover just under a ‘square’. Valleys will also add extra bundles of ‘area’ shingles. My formula for valleys is simply the length of the valleys times 2, to be added to the total roof area.
Besides coverage for the roof’s surface area, you will need bundles to cover the ridge and bundles to cover the layer of under-course shingles around the roof edge’s outside perimeter. You’ll need a bundle of 3-tab shingles for every 30 feet of ridge line and a bundle for every 65 feet of outside roof perimeter.
When ever I measure up a roof, I like to sketch the roof out on a piece of paper and record the length of each roof edge and write up any issues that need to be addressed. Total area is simply a sum of all the areas of each roof section, calculating each using a simple length X width formula. This total area will give you the number of bundles required to cover the area. You’ll need the total length of all outside roof perimeters, the total length of all ridges, the total length of all valleys, the total length of all vertical walls going up along slopes and the total length along walls that run horizontally to the roof.
The outside perimeters of your roof will require a metal roof edge flashing. This metal roof edge comes in 10 foot lengths. Simply take your total outside roof perimeter and divide by 10 to get the total number of pieces.
You will need rolls of ice dam protection. Ice dam protection comes in 3’X65′ foot rolls. It is sometimes referred to as ‘peel and stick’ because you have to peel off the underside to glue onto your roof’s bottom eave’s and down the length of your valleys. To estimate how many rolls you need, add up the lengths of your bottom eaves and valleys and divide by 65. Wherever your bottom eave has an overhang greater than 2 feet, you should double that length of that portion of eave.
You will also require a roofing paper underlayment to be installed prior to shingling. Roofing paper provides a second barrier of protection. It also provides a very quick way to cover the roof after you’ve torn off and disposed of the old roofing materials. There are two options available: the old 15 lb. felt paper or the new synthetic. I prefer the synthetic roofing paper because it’s tougher. I it is difficult to pull up once it’s properly nailed or stapled down. This is important if you are going to leave your roof exposed overnight without shingles, particularly if you live in an area prone to high winds. Felt papers tend to buckle a lot if left exposed for even a short length of time and tends to lift easily in high winds. Synthetic paper is a little more costly, but for me, the security is worth it. A roll of synthetic paper covers about 1000 square feet of roof area.
If you plan to install a ridge vent on your roof, they come in different lengths depending on the manufacturer. The one that I prefer is 30 feet long. You can only install them on a horizontal ridge.
This will give you the bulk of the materials needed. You might want to throw in a couple sheets of plywood in the event you find some rotted roof deck sheathing.
If you are hand-nailing you can estimate about a pound of 1 1/4″ roofing nails for every square of roof area. If you are using an air-gun, a single coil will allow you to nail down about a bundle and a half using 1 1/4″ nails. You’ll need a coil of 1 3/4″ for every 20 feet of ridge cap and installing the ridge vent.
Number of flashings required around pipes and walls will depend on whether or not they need replacement.
It never hurts to overestimate the amount of material required. Most material outlets will take back and refund excess material as long as it has not been damaged. It’s tough to find out that you are short of material, when you are exhausted, at the end of the day.
Bring your list of materials to a few suppliers and get several quotes to find the best price.
After all that, you decide that it’s just too much to handle on your own, you may decide to simply hire a roofing contractor. In my next post I want to discuss the pros and cons of hiring a roofing contractor. Roofing contractors have a bad reputation for being disreputable. I hope I can give you a few sound tips on hiring out.