The first question that needs to be answered when you want to know the price of a self adhered modified butimen roof from Mulehide is, how long of a warranty would you like?
For example, Mulehide offers a 10, 15, and 20 year warranty, but it depends on the number of layers you buy for your roof. If you buy a base layer plus the cap layer, you get 10 years of warranty.
If you buy a two base layers and one cap layer, then Mulehide secures you a 15 year warranty. The longest warranty Mulehide offers residential flat roof customers is 20 years. In order to earn the 20 year length warranty the homeowner must have a nail base layer (to fully protect the decking), two base layers, and 1 cap sheet layer of self adhered modified bitumen membranes.
Flat roofs, when installed correctly, can be wonderful for a long time. Unfortunately, residential flat roofs have the most complaints from homeowners because the roof contractors they hired said they had flat roof experience, but didn't solve the details that cause leaks to the homeowner. Roof technology can be split into two categories: 1. water shedding technology 2. water proofing technology.
Clay tile roofs are an example of water shedding technology. Self adhered modified bitumen, TPO, and modified torch are examples of water proofing roofing technologies. Water proofing is a big responsibility that requires an obsession to detail. Most roofing companies don't have the patience to obsess over the water proofing a skylight needs or the waterproofing a pipe jack perforation needs to truly keep the water out of the interior of your home for decades to come. Is it impossible to waterproof a flat roof? No, it isn't impossible. But there is a direct correlation between the number of layers of self adhered mod bit and the quality of waterproofing.
We've identified the possible points of failure, so how much is going to cost you?
Here is an example for most of the materials list from a bid given to a homeowner in Briargrove neighborhood located in Houston, Texas. The homeowner chose a 15 year warranty (Nail base, 1 base layer, and 1 cap sheet layer).
The roof measures 2,642 square feet, and because the self adhered modified bitumen membrane comes in small rolls, we don't have to add much waste percentage.
Heavy Roller minimum 75 pounds (should be either included in the price, although some companies will charge rental fee)
Nails Price List (usually the first 1000 nails are included):
1-1/4" Coil Nails $57.99 per box
1-1/4" EG Roof Nails - 50 #/BX $65.99 per box
1" Plastic Cap Nails 2000 Box $26.99 per box
1-3/4" Coil Nails $74.99 per box
1/2" Plywood Clips $16.99 per box
Labor for tear down, roofing, cleaning, disposal of debris $6200
Qty 32 Sticks of 6 Inch Drip Edge 10 linear feet sticks $20.50 per stick = $656.00
3 - Step Flashing Per Bundle 8ft x 8 ft $64 each = $192
Equipter RB4000 Rental Per Day $300
Dumpster for debris - Included in Overhead
16MH1215 - 5 gallon Mulehide 121 Asphalt Primer - 16MH12114 Spray Can 15 oz
16MH4213 - 5 gallon 421 Mod Bit Flashing Adhesive (3 gallon available)
Qty 18 - Rolls of 06MHSANB - MuleHide SA Nail Base 2 SQ/RL $97 each - $1746
Qty 18 - Rolls of 06MHSAB - MuleHide SA BASE SHEET 2SQ/RL $99.25 each - $1786.50
Qty 33 - Rolls of 06MHSAAHB - MuleHide SA-APP CAP SHEET HEATHER BLD 1SQ $96.75 each = $3192.75
Shipping of Materials $100
Sales Tax 8.25%
Ask different roofing companies which is the best option for a residential flat roof and each of them will focus their answer on what is most profitable to them, not what is the best solution for your home and your family.
Here is an example: the roofing company that specializes in selling coatings will tell you not to change your flat roof. They will insist of adding another layer of roof to your existing structure by adding a coating. Their input costs are rock bottom so most of what they charge you is all profit. They prefer this route because there is a large price gap between coatings and the next option: namely, modified torch method.
The roofing companies that like the modified torch method will tell you this is your only option because TPO and Self Adhered Mod Bit are inferior choices. The truth they don't disclose is that they don't have the people to properly do self adhered mod bit, TPO provides less margins for them, and the modified torch is their method of choice because they have most profits relative to input costs.
Personally, I think it is irresponsible to have an open flame on a residential roof with a pool in the backyard. I don't recommend modified torch for a home because of the fire hazard involved. The reward isn't worth the risk. We would rather have less margins, but offer the safer method to you and your family. The flat roof homes with pools require phosphorous testing after the modified torch installation to ensure your pool's water is safe for your family. Most roofing contractors don't want you to know that, either.
After you add everything together, expect to pay between $6.00 per square feet to $7.50 per square feet. Could you pay less than that? Perhaps you could pay more, but if price is what you pay and value is what you receive, then what are you not getting from the less costly bid?
Roofing companies take shortcuts on the accessories. Some roofers that charge you less will re-use parts of your old roof and bill you as if you were getting new ones. Unethical practices by budget roofing companies plague the industry. Ask for detailed estimates to avoid being duped by roofers.