What’s The Difference Between a Dry and Wet Roof Fixing Method?

This page forms part of our blog which contains a series of hint, tips and advice for consumers and tradespeople.

Whether you’re working in the trade or are a homeowner looking to make sense of the odd terms used in the construction industry, this guide is for you.

What is a wet roof fixing method?

Any fixing system that claims to be “wet” is one that uses cement as the primary method to secure the roof tiles in place.

The photo below shows ridge tiles being bedded onto cement:

 

Why Wet Systems Fail

While most people think that cement is a strong material that’ll last forever, the truth is often very different.

When a roof on a typical house is constructed, the weight of the tiles presses down onto the roof timbers and there’s some flexing and movement.

Most new houses will experience between 5-30mm of movement in the roof. This usually occurs within the first few years after construction.

While this is quite normal, it does have an effect on the cement which is holding the tiles in place.

Cement doesn’t like movement, it often cracks, can crumble and during installation is also susceptible to frost and rain.

The end result is often something similar to this:

Failed cement and loose ridge tiles

The problem with cement is that it cracks, fails and the tile can come loose.

Needless to say, a loose tile like this could be blown off the roof on a windy day and potentially kill someone.

Changes to British Standards (BS 5534)

In 2010 the NHBC (National House Builders Council) saw a 60% increase in the number of claims relating to pitched tiled roofs.

Most of the claims were as a result of cement failure.

This, along with an increase in adverse weather, led to several changes in the requirements of British Standards.

These changes are now in force.

BS5534 states that cement can no longer be used as the sole means of securing roof tiles in place.

To meet the new requirements, a mechanical fix such as a screw or clip should be used.

The Dry System

The dry fix system secures the roof tiles to the roof without any cement whatsoever.

Take a look at the photo below:

As you can see, a clip secures the tile into place and allows for plenty of movement, there’s no cement to crack and the tile can shift and move with the roof without breaking loose.

This type of fixing system is now used on almost all new build roofs.

It’s also becoming more popular on refurbishment projects.

The Hybrid Fixing System

The hybrid fixing system is one that uses cement for aesthetic purposes whilst adding a clip system to guarantee that the tiles won’t come loose.

Below is a photo of a wet system and a dry system combined, i.e a hybrid:

 

The Pros and Cons of Each

Below you can see the pros and cons of the wet fix, dry fix and hybrid systems:

The Wet Fix System

Pros

  • looks traditional
  • will blend in neatly with neighbouring roofs if you’re using it on a refurbishment project

Cons

  • can crack and tiles may come loose (more likely on new homes because the roof takes a few years to settle)
  • time consuming
  • cement will fail if the temperature drops below freezing before the material has set
  • cannot be laid in the rain

The Dry Fix System

Pros

  • quick and easy to lay
  • can lay in rain and cold weather
  • it’s quick to learn this installation method
  • secure tiles with little chance of them coming loose

Cons

  • not as aesthetically pleasing as cement
  • may look out of place on a traditional property
  • potential issues with listed buildings

The Hybrid System

Pros

  • secures the tiles
  • keeps the roof looking aesthetically pleasing

Cons

  • takes the most amount of time to complete
  • cement cannot be laid on wet or cold weather

What About Building Regulations and “The Law”

The British Standard (BS 5534) does not form part of the building regulations and is not enforceable by “the law”.

British Standards only apply to roofers that have agreed to abide by the requirements.

A good example of this is house builders that offer a 10-year NHBC guarantee. The NHBC require all roof tiles to be fixed in accordance with British Standards.

While this agreement is not “the law”, it does form a contract which could be enforced through a civil court.

If you comply with a British Standard then it’s pretty clear that you take your responsibilities seriously as an organisation, and indeed compliance is often taken as evidence of due diligence. It certainly speaks volumes about your attitudes to doing things properly. However, standards aren’t the same as regulations and following a standard doesn’t guarantee that you’re within the relevant laws. – BSI Group

What About Refurbishments?

Many roofing firms are now using either the dry or hybrid fixing system for refurbishment projects as well as newly built homes.

While most people feel that the British Standards are “best practices”, there are some reasons why a roofing firm may consider a wet system instead:

  • the property is listed/graded
  • for purely aesthetic reasons
  • the property is in a very sheltered location
  • the roofer feels that the roof has settled and is unlikely to experience any further movement and a wet system will suffice

Our Recommendation

We recommend that all roofers use either the dry or hybrid system unless there are valid reasons not to, such as the property being listed.

Other Types of Tile That Can be Dry Fixed

The photos further up on this page show ridge tiles and the various fixing methods.

Similar fixing methods also apply to verge, hip and other tiles.

See the photos below:

Plastic dry verge system

Hip system with clips for cut tiles

Get a Quote

If you need a quote for roofing work, just hit the link below and fill out the form.

It only takes 2 minutes to get the ball rolling:

Get a Quote Online

© www.job-prices.co.uk

close

Copy and paste this code to display the image on your site