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Spray Foam Insulation

Can I Insulate My Slate Roof With Spray Foam?

Can I Insulate My Slate Roof With Spray Foam

Insulation inside your loft is one of the best ways to keep your home warm and spray foam insulation is always the best choice.

Being more flexible, easier to use, more thermally protective and longer lasting – spray foam is becoming a more popular choice for homeowners. However, you may have concerns that your slate roof may be ruined by the application of spray foam and as with most things there are positives and negatives.

What Is A Slate Roof?

In parts of the UK slate is a very popular and attractive choice for covering a roof. It is a natural product that is considered to be one of the longest lasting and highest quality roofing materials you can choose.

It offers a beautiful grey through to black appearance and the varying sizes and thicknesses of the slate tiles gives your roof a more rustic appeal.

You can usually expect your slate roof to last around 100 years – compared to other roofing materials that expect to last around 30 years. With high resistance to fire and an environmentally friendly reputation it is easy to see why slate is so popular.

However, there are some negatives to take into account with slate tiles. They are one of the most expensive roofing materials due to the difficulty in mining for the product.

They need to be carefully installed and can add considerable weight to your roof structure – therefore they must be carefully installed by an experienced contractor.

In some cases, slate tiles can be subject to higher levels of breakage due to their natural structure. Tiles made of slate will have breakage points and can be very fragile, especially when being laid.

Can I Insulate My Slate Roof With Spray Foam

Although an attractive choice for covering a roof, slate tiles should only be installed by an experienced contractor to ensure they remain fully intact as the years go by

Spray Foam: The Basics

When it comes to insulating your home, spray foam is one of the best choices. Spray foam is created by combining two chemicals under high pressure.

This results in a liquid that quickly expands to 9 times its original size, filling gaps and creating a waterproof and strong insulation. It can be used in most circumstances and is especially useful when it comes to filling gaps that are hard to reach or awkward.

Spray foam comes in two basic types: closed cell and open cell. Closed cell can be used for structural purposes and makes a good sound barrier. Open cell contains air pockets and is therefore more breathable. This makes it an excellent insulator and is perfect for walls and roof insulation.

The Energy Saving Trust recommends that you use 270mm of mineral wool insulation to achieve the correct levels of energy efficiency inside your loft. This can cause head height issues.

The same thermal protection can be achieved from just 100mm of spray foam insulation. This makes it ideal for small loft rooms and will take up much less space.

You can usually expect your spray foam insulation to last as long as 30 years – although there are indications that it can last much longer than this. Despite it being a more expensive option, the fact it lasts so long makes it cheaper in the long run.

Can I Insulate My Slate Roof With Spray Foam

Spray foam offers substantial support to slate roofing, with both products working well in tandem to ensure your roof's resilience long-term

Insulating A Slate Roof: An Overview

Spray foam used to insulate your roof will almost always be used in the same way. It is sprayed directly onto the underside of your roof structure from the inside. Layers of foam are applied between the rafters and then either left as it is or covered with plasterboard.

The main concern people have with applying spray foam in this way to a slate roof is that many of these roofs are constructed with no barrier between the slate and the inside of the loft.

In other words, the spray foam adheres to the slate directly. As you might expect, there are pros and cons of this approach:

Pros Of Spray Foam For Slate Roofs

● Spray foam does an excellent job of protecting the slate tiles on your roof and strengthening them. Any tiles that are starting to fail will be given a few more years of life by having this additional structural element added to their underside.
● If you are finding that your slate roof is starting to leak, spray foam will work well to plug these gaps. Spray foam is entirely waterproof and therefore will not allow any water to penetrate.
● If open celled spray foam is used, the roof will continue to breathe and there should be no build up of condensation in the loft. This is the case, even if water penetrates the tiles and reaches the spray foam layer.
● Spray foam and slate roofs have a similar shelf life and therefore work well together as insulation. In fact, spray foam can ensure your slate tiles last even longer.

Can I Insulate My Slate Roof With Spray Foam

Is your slate roof suitable for spray foam insulation? A free site survey will help you assess whether foam would be feasible, and, if so, the issues it can help you address

Cons Of Spray Foam For Flat Roofs

● If you decide to change your slate roof at any time in the future, the slate will not be able to be used elsewhere or recycled. It will have spray foam adhered to the underside of every slate.
● It is harder to replace sections of the roof if needed without disturbing the spray foam underneath – it is likely the spray foam will need to be replaced at the same time. This will add to the cost of reroofing in the future.
● You should take the time to replace old or broken tiles and repair any obvious defects on your roof before adding the spray foam insulation. This can add to the cost of the job, but will increase the amount of time the roof will last.
● Spray foam will add to the overall weight of the already heavy slate roof. This should be taken into account by your contractor to ensure the roof struts can take the weight. You may require additional structural work to be undertaken and this can add to the cost.

Spray Foam For Slate Roofs: Final Verdict

Overall, spray foam insulation when used on a slate roof will ensure it lasts longer and will provide additional structural support. The main areas of concern are that replacement of the roof in the future will be a more costly and time consuming job and the slates cannot be reused.

However, it is worth bearing in mind that your slate roof is expected to last a century and after this time the slates will be crumbling and ineffective as a roofing material, in any case. You could even extend that life by using spray foam – therefore getting even more from your roof.

Whatever you choose to do, getting the right contractor to fit both your slate roof and your insulation is essential. A good roof that has been correctly laid will be the starting point to an excellent spray foam insulation job.

You should not use the insulation to repair your roof – always try to start with a slate tiled roof that is in good repair and you will have many years of maintenance free roofing.

Ready to transform your roof-space into a a fully habitable room? With spray foam insulation, you can achieve exactly that! Request your free roof survey today by calling 0800 1700 636, or by simply clicking the button below!