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Why the removing of an old roof is not necessary for a new roof installation

See why it is beneficial to install a torch down unto an existing torch down rubber roof.

When commercial buildings need a new roof, there is no reason to remove the old roof before installing the new rubber roof. In my thirty years of roofing, I had only removed one old roof to prepare for a new rubber roof, and that was a mistake. The image below the video is that roof we removed. That roof ended up costing three times as much to install, with no added benefits.

Flat-Roof-Installation
Installing the first layer of a Modified Bitumen Torch Down Rubber Roof

Why it is not necessary to remove the old Gravel and Tar roofs?

Most existing roofs already have insulation and added materials to pitch the roof a certain way.

What are the advantages of leaving an old roof in place and re-roofing over it?

The drains are already in place. it is expensive to replace all the drains

Why keep old roofs intact and re-roof over them?

The metal flashing against parapet walls, air conditioner curbs, and skylights are already in place. No need to replace all the flashing

Why not remove old roofs?

Most commercial roofs already have metal caps or build-in flashing on the parapet walls. To replace them would be unnecessary

Why not remove an Old Torch Down Roof?

If an old roof has an existing Modified Bitumen Torch Down Material, it is far more beneficial to fuse a new layer of Torch Down over the existing. This method will ensure a roof to last beyond 40 years.

Why install a new layer of roof over an old roof?

Installing over an existing roof reduces cost by more than 60%

Why install a roof over and existing roof?

The old roof build-up allows that drains can be lowered to create positive water flow. Some of the old roofing material can be removed around the drain areas helping to cause a pitch

Flat Roof Installation on a commercial roof

We specialize in the Installation of a Two-Ply Rubber Roofing System. on commercial buildings. This system comprises of 2 layers of Modified Bitumen Torch Down Rubber Membranes that are fused together. By adding a second layer, it makes this type of roofing superior to any other roof.

The Two-Ply Modified Bitumen Torch Down Rubber roof outperforms Single Ply EPDM or TPO Roofing Systems. The Two-Ply Torch Down roof can be installed almost over any surface including stone and other roofing membranes making it a very cost-effective roof that will outlast all other roofs.

A 40-year warranty comes with the Two-Ply Rubber Roofs we install.

Preparing the surface for installing a new rubber roof. Use leave blower
This is an image of a roof that was installed without proper draining or planning. On top of that, the roof technician did not know how to weld seams correctly, hence the tar everywhere.

A check-list to consider before installing a new roof:

  • Planning a drain system is the most crucial aspect when considering a new roof. Most flat roofs have drain issues.
  • To decide which roofing system to install.
  • To find a roofing contractor that can perform the best job.
  • To get a proper estimate of the cost of the installation.

When it comes to Flat Roof Installation, the fewer obstacles on a roof the less the installation cost will be. Try to eliminate unnecessary objects like air conditioners, ductworks, skylights, bathroom vents. The less obstruction a flat roof has, the faster the installation the lower the cost will be.

Remove old a/c units prior to the Installation of a new roof
Before installing a new flat roof, it is good practice to remove old air conditioning units from the roof.

What are roof vents for?

These roof vents are designed to remove dampness from under the roof surface. They are not always beneficial and removing them will do no harm. Some roofing contractors install these vents to ensure in the event their roof leaks, that these vents will allow the underlayment to dry.

Remove air-vents from roof
In this image is a roof vent that helps to remove dampness from the underlayment on a flat roof.
Gravel Rock roof surface - Steps taken of installing over this surface
In this image is a Hot tar and gravel roof.
This video demonstrates the installation of a Torch down rubber Roof over Tar and Gravel roof.

Preparing the Surface is key

Remove debris from the roof
Remove unnecessary obstacles like unused vent pipes, left behind A/C units.
Remove old roofing material off from existing flashing
Clean drain areas by removing roofing materials to expose drain flange
Clean scupper areas to expose the copper

Preparing an old Gravel Stone Surface for a new Torch Down rubber roof.

Rake the gravel rock around to level off the roof.
Move loose rock to lower areas to build up the area
After raking the gravel making a smooth surface and removing clumps and larger rocks, install a fiber base paper by using long screws and anchor plates purchased from a roofing supply warehouse. Make sure the fiberglass paper is not wrinkled when anchored down spacing the anchors every 2 feet. Be careful not to cover the metal flashing and drip edges.
Install a Modified Bitumen Self-Adhering Base over the fiberglass base. Be careful not to include any metal parts.
Torch Down a Modified Bitumen Rubber Membrane with ceramic granules embedded to the self-adhering membrane fusing them together.
Use special adhesives to attach the Torch Down Rubber to the flashing and other metal areas.

Installing over an existing Modified Bitumen Rubber membrane
If the surface has a fresh coating of Aluminum Asphalt Coating (silver paint) then skip this step and follow Step 3
If the surface has a pretty worn down coat of silver paint and flaking off, then sweep brush any loose paint and debris off the surface. Use a leave blower to get the dust off.
Look for any wrinkles in the membrane and cut them away.
Remove the existing roofing membrane from existing flashing to expose the flashing around skylights, vents, walls and where necessary.
Fill areas where water would normally pond by installing an ISO board over the existing roofing membrane.
Lower areas around a drain area by removing roofing material.
Install a self-adhering Modified Bitumen Base membrane in the areas where the surface had to be build up and where roofing material was removed to lower the roof.
Torch Down a Modified Bitumen Rubber Membrane with ceramic granules embedded in the self-adhering membrane fusing them together.
Use special adhesives to attach the Torch Down Rubber to the flashing and other metal areas.

Aluminum Asphalt Coating (silver paint)

If the existing roof has a coating of Aluminum Asphalt (silver paint) but is mostly peeled off or 80% of the membrane is exposed, then it is advisable to install a membrane directly onto it with a torch fusing the new membrane with the existing rubber membrane.

Detailing

Once the Modified Bitumen Torch Down Rubber is fused to the Self Adhering base, it is time to take care of the details. On every corner of skylights and a/c unit curbs and around every vent pipe, particular attention must be given to make the necessary patches.
Use special adhesives to make necessary seals around skylights, A/C units, and vents, vent pipes, and pitch pockets.
Attach the rubber membrane to the drain or scupper with special adhesives.

Cleaning up

Pick up all loose roofing materials
Use a leave blower to blow the roofing surface clean.
Walk around to make a final inspection to see if all detail is taken care off.

Step 2 a –Preparing an old Gravel Stone Surface for a new Torch Down rubber roof.

  • Rake the gravel rock around to level off the roof.
  • Move loose rock to lower areas to build up the area
  • After raking the gravel making a smooth surface and removing clumps and larger rocks, install a fiber base paper by using long screws and anchor plates purchased from a roofing supply warehouse. Make sure the fiberglass paper is not wrinkled when anchored down spacing the anchors every 2 feet. Be careful not to cover the metal flashing and drip edges.
  • Install a Modified Bitumen Self-Adhering Base over the fiberglass base. Be careful not to include any metal parts.
  • Torch Down a Modified Bitumen Rubber Membrane with ceramic granules embedded to the self-adhering membrane fusing them together.
  • Use special adhesives to attach the Torch Down Rubber to the flashing and other metal areas.

Installing a Two-Ply Rubber Roof over Tar and Gravel

A Two-Ply Modified Bitumen Torch Down Rubber membrane was installed over this Tar and gravel surface. As long as the big stones are removed and the gravel is raked evenly.

Gravel Rock Roof - Installing a 2 ply over this surface is fine
The image above was taken right before installing a Two Ply Torch Down Rubber Roof

In the Process of installing a Two-Ply Rubber Roof over gravel

There is no telling that the new Torch Down Rubber is on a tar and gravel roof when walking on it. It is super tough and no foot traffic or any workman will be able to damage it.

In the process of Installing a Two Ply Rubber Roof over a gravel Rock roof
The image above shows a Torch Down Rubber Roof in the process of installation

Step 2 b – Installing over an existing Modified Bitumen Rubber membrane

  • If the surface has a fresh coating of Aluminum Asphalt Coating (silver paint) then skip this step and follow Step 3
  • If the surface has a pretty worn down coat of silver paint and flaking off, then sweep brush any loose paint and debris off the surface. Use a leave blower to get the dust off.
  • Look for any wrinkles in the membrane and cut them away.
  • Remove the existing roofing membrane from existing flashing to expose the flashing around skylights, vents, walls and where necessary.
  • Fill areas where water would normally pond by installing an ISO board over the existing roofing membrane.
  • Lower areas around a drain area by removing roofing material.
  • Install a self-adhering Modified Bitumen Base membrane in the areas where the surface had to be build up and where roofing material was removed to lower the roof.
  • Torch Down a Modified Bitumen Rubber Membrane with ceramic granules embedded in the self-adhering membrane fusing them together.
  • Use special adhesives to attach the RorchDown Rubber to the flashing and other metal areas.
Installing over an existing Modified Bitumen Rubber Membrane - Cut away the wrinkles
This image shows a Torch Down Rubber Roof that was not installed correctly

Step 3 – Aluminum Asphalt Coating (silver paint)

If the existing roof has a coating of Aluminum Asphalt (silver paint) but is mostly peeled off or 80% of the membrane is exposed, then it is advisable to install a membrane directly onto it with a torch fusing the new membrane with the existing rubber membrane.

A Modified Bitumen Torch Down Rubber Roof with Aluminum Asphalt coating (silver paint)
Torch Down Rubber Roofs in Brooklyn and Manhattan are popular roofs since the 60’s

Existing Modified Bitumen Torch Down Roof

An Existing Modified Bitumen Torch Down Roof is ready for a new layer. Fusing the two together becomes an indestructible roof that will last beyond 40 years. If there is silver paint between the twp layers, then the two layers won’t be able to melt together.

A modified Bitumen Torch Down Rubber Roof ready for a new layer.
A Torch Down Rubber Roof that is over 20 years old. The protective coating is warn away

This EPDM Rubber Roof already had several patches. This is a perfect example of a roof that can be covered with a Two Ply Modified Bitumen Torch Down Rubber membrane.

Step 2 d – Plywood Substrate or Decking

  • Install the necessary insulation with fasteners
  • Install Modified Bitumen Self-Adhering Base over the insulation
  • Install metal flashing where necessary.
  • Install drip edges
  • Torch Down a Modified Bitumen Rubber Membrane with ceramic granules embedded in the self-adhering membrane fusing them together.
  • Use special adhesives to attach the RorchDown Rubber to the flashing and other metal areas.
Steps on how to install a rubber roof over plywood or decking

Step 3  – Detailing

  • Once the Modified Bitumen Torch Down Rubber is fused to the Self Adhering base, it is time to take care of the details. On every corner of skylights and a/c unit curbs and around every vent pipe, particular attention must be given to make the necessary patches.
  • Use special adhesives to make necessary seals around skylights, A/C units, and vents, vent pipes, and pitch pockets.
  • Attach the rubber membrane to the drain or scupper with special adhesives.
After installing the final layer, details like corners of skylights and a/c units must be sealed

Step 4 – Cleaning up

  • Pick up all loose roofing materials
  • Use a leave blower to blow the roofing surface clean.
  • Walk around to make a final inspection to see if all detail is taken care off.
Walk around on the roof and inspect every detail and see if you missed anything

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