Thinking About Roof Sheets for Your Home? Here Is My Straight Answer

When customers ask me about roof sheets, it is usually for garages, lean-tos, sheds, carports, side returns or budget extensions. They want something quick, affordable and reasonably tidy without getting into a full traditional roof build.

In my 18 years on the roof around Brighton, Hove and Worthing, I have installed, repaired and ripped off more sheeted roofs than I can count. Some have worked brilliantly for 20+ years. Others have failed in under 5 because the wrong sheet was used, or it was fixed badly.

In this guide I will walk you through the main types of roof sheet, where I would (and would not) use them, the common problems I see, and how to decide if a sheeted roof is right for you or if you should be looking at a proper flat roofing system instead.

The Main Types of Roof Sheet I See on Sussex Homes

When you say “roof sheet”, it can mean a lot of different things. Here are the ones I deal with most often:

1. Metal Roof Sheets (Steel or Aluminium)

These are the corrugated or box-profile sheets you often see on garages, workshops and outbuildings.

  • Pros: Tough, fairly long-lasting if coated properly, fast to install, good for shallow pitches.
  • Cons: Can be noisy in rain and wind, can condensate badly if not detailed correctly, not very “domestic” looking on some houses.
  • Best for: Garages, workshops, farm buildings, modern industrial-style garden rooms where the look suits the property.

If you ask me, on a typical Brighton or Hove terraced house, metal sheets on the main house usually look out of place, but they can work fine on a rear garage or garden building if done neatly.

2. Polycarbonate Roof Sheets

These are the clear or tinted plastic sheets you see on older conservatories, lean-tos and covered walkways.

  • Pros: Let in lots of light, lightweight, relatively cheap, easy to cut to size.
  • Cons: Can be very noisy in heavy rain, can look tired and discoloured after years of UV, not great for insulation, can leak at joints if the right trims and tapes are not used.
  • Best for: Simple lean-to covers, carports, storage areas where you want daylight more than perfect thermal performance.

When customers ask me whether to use polycarbonate over a new kitchen extension, my honest advice is usually no. It is fine for a basic cover, but it rarely gives the comfort, insulation and quiet that you want over a lived-in space.

3. Bitumen Corrugated Roof Sheets

These are the dark corrugated sheets you often see on sheds or cheap garages.

  • Pros: Cheap, light, reasonably quiet in rain compared with metal, simple DIY-style fixing.
  • Cons: Shorter lifespan, can become brittle and fade, often leak where nailed or screwed if not sealed properly, more “temporary” than long-term.
  • Best for: Garden sheds, budget storage roofs, temporary covers.

In my opinion, bitumen sheets are okay if you accept they are a basic, lower-lifespan choice. I would not put them on a main garage you really care about keeping dry long-term if you can stretch to something better.

4. Fibre Cement Roof Sheets

These look similar to old asbestos sheets but are asbestos-free modern products.

  • Pros: Long-lasting, decent fire resistance, good for condensation control compared with plain metal, fairly robust.
  • Cons: Heavier than metal or plastic, more “agricultural” in appearance, requires proper fixings and support.
  • Best for: Agricultural buildings, some garages, commercial and light industrial units.

A lot of older garages and workshops in Sussex still have the original asbestos cement sheets. When I am asked about replacing them, I always recommend using modern, non-asbestos equivalents or upgrading to a proper flat roof system depending on the building.

Roof Sheet vs Proper Flat Roof: What I Tell Customers

On many site visits I end up having the same conversation: “Should I just stick sheets on this, or should I do a proper flat roof?”

When Roof Sheets Make Sense

I usually say roof sheets are reasonable when:

  • The building is unheated or low-value (shed, simple garage, log store).
  • You mainly want shelter from rain, not full warmth and quiet.
  • The budget is tight and you accept a shorter lifespan.
  • You are keeping the job fairly simple and accessible for future changes.

When I Recommend a Proper Flat Roof Instead

For many domestic jobs in Brighton and Hove, a decent flat roof system is a better long-term bet than sheets. That includes:

  • Garage roofs you rely on to keep things genuinely dry.
  • Rear extensions and kitchen/dining extensions.
  • Porch roofs that are part of the main front elevation.
  • Bay window tops that need to be watertight and look smart from the street.

If you are considering upgrading a sheeted roof to something solid and long-lasting, you can use my garage flat roof cost calculator to get an instant idea of price before you commit to anything.

For full rear extensions where you want insulation, neat finishes and a proper warranty, I usually install high-performance torch-on felt systems. You can see how I approach that kind of work on my rear extension flat roof service page.

Common Problems I See With Roof Sheets

Most roof sheet failures I get called out to are not because the sheet is “bad” as a product, but because of how it was installed or detailed.

1. Condensation Dripping Inside

Metal sheets in particular can suffer badly from condensation. Warm, moist air from inside hits the cold underside of the sheet and turns to water, which then drips onto cars, tools and stored items.

To reduce this, you need the right combination of:

  • Ventilation (airflow to carry moisture away).
  • Insulation in some situations.
  • Anti-condensation coating or liner sheets where appropriate.

If the building is important to you, sometimes it is simply more sensible to move away from bare metal sheets and go for a warm flat roof build-up instead.

2. Leaks at Fixings and Overlaps

Another common issue is water creeping in where the sheets are screwed or nailed down, or where they overlap each other. Over time seals harden, fixings loosen or the wind lifts the sheets just enough for capillary action to start dragging water in.

On a quick inspection I can normally tell you straight away whether the leak is a simple fix (like replacing a few failed fixings) or whether the whole sheet arrangement is past its best. If you are unsure where the water is getting in, you can always book a free roof inspection in Brighton or Sussex and I will trace it for you.

3. Noise in Wind and Rain

One thing homeowners do not always think about is noise. A metal or polycarbonate roof sheet can be surprisingly loud during heavy rain, hail or strong winds, especially if the sheets are not supported and fixed properly.

On a simple workshop this might not bother you. Over a kitchen or bedroom it can drive you mad. In those cases I nearly always advise a more solid, insulated flat roof rather than bare sheets.

4. Poor Edging and Guttering

I see a lot of sheet roofs where the sheets just dangle off the edge with no proper trims, flashings or guttering. Water then runs back under the sheet, rots the timber, and causes damp patches on walls.

A neat barge detail, correct verge trims, and properly sized guttering make a huge difference. If the sheeted roof is staying, upgrading the guttering is often one of the best value improvements you can make. When I am replacing or improving eaves, I often combine it with new guttering and downpipe installation so everything works together.

Roof Sheets on Balconies, Terraces and Walkways

Sometimes people ask me if they can sheet over a flat roof terrace or balcony to keep the area dry. Technically you can, but you need to think carefully:

  • Head height and planning issues.
  • Fire safety if it adjoins your main house.
  • How it will look from your own windows and the neighbours’.
  • How rainwater will be managed.

For many balconies and roof terraces, my approach is to keep the roof itself fully waterproof and robust, then focus on finishes and drainage rather than cladding it all with sheets. You can see how I handle that kind of project on my balcony and roof terrace waterproofing page.

When a “Quick Sheet Job” Becomes a False Economy

Here is my honest advice: a roof sheet can be a perfectly sensible solution in the right place, but it can be a complete false economy in the wrong one.

In my 18 years on the roof, I have noticed the same pattern:

  • Cheap sheets go on a garage or lean-to as a “temporary” fix.
  • No proper gutters or flashings are fitted to save money.
  • Within a few winters, leaks, condensation and rot appear.
  • In the end, the whole roof needs replacing properly anyway.

If the structure itself is sound and you plan to keep using it for years, it is often better value in the long run to do a solid flat roof from the start. For example, if you have a garage attached to the side or rear of your home, it is usually worth looking at a proper felt system like I use on my main flat roof projects in Brighton and Hove.

How I Help Customers Decide on Roof Sheets vs Flat Roof

When I come out to see you, I do not just push one option. I walk you through:

  • What the building is used for (storage, living space, hobby room, workshop).
  • How long you want it to last realistically.
  • What the noise and condensation risks are.
  • How the finished roof will look from the street and the garden.
  • Your budget now, vs the cost of doing it twice.

If a decent metal sheet job will genuinely serve you well, I will say so. If I think you are about to waste money on something that will annoy you in two winters’ time, I will tell you that straight as well.

What To Do If Your Existing Sheet Roof Is Leaking

If your current roof sheet is leaking, you have three basic options:

  1. Patch the worst bits – replacing failed fixings, masticing overlaps, adding flashings. This is usually a short-term fix.
  2. Re-sheet like-for-like – if the structure is sound and the sheet type still makes sense for how you use the space.
  3. Upgrade to a different type of roof – usually a warm or cold flat roof system with proper waterproofing.

If the leak is urgent and you are worried about damage spreading, you can use my priority emergency roof leak booking service so I can make things safe and watertight as quickly as possible.

Final Thoughts: Is a Roof Sheet Right for Your Project?

To sum it up in simple terms:

  • Yes, consider roof sheets for sheds, basic garages, lean-tos and areas where you mainly want rain cover, not high comfort levels.
  • Think twice before using them over living spaces, important garages, or anywhere noise, looks and long-term reliability really matter.
  • Plan the details properly – fixings, overlaps, flashings, gutters and ventilation are just as important as the sheet itself.

If you want straight, no-nonsense advice on your particular roof, I am happy to come out, have a proper look and talk you through the options in person. No pressure, no sales pitch – just my best recommendation based on what I would do if it were my own property.