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Improvements to Part L of the Building Regulations have ensured highly insulated roofs and this, coupled with heavy snowfall, has the potential to cause gutter problems.

When a thaw sets in the snow will slide down the roof, taking with it anything in its path including gutters fitted too high under the roof edge. Prior to the installation of a highly insulated roof, the snow would merely melt as it fell onto the roof surface.

Traditionally, eaves gutters have been installed as high as possible under the roof edge to ensure that overshooting of rainwater does not occur and/or to hide an unsightly roof edge. It also had the advantage of providing protection against wind driven rain but also means that there is a higher risk of damage by sliding snow.

Three important points when installing guttering

  • British Standard BS 5534 states that roof tiling should project a minimum of 50mm from the vertical face of the fascia board
  • Different types of roof surfaces will create either more or less projection of discharge at the roof edge; for example, water will flow faster down a smooth tile than a granular tiled roof.
  • Greater care must be taken to make sure the gutters will not impede sliding snow. BS EN 12056: 3-2000 suggests that snow guards should be fitted where sliding snow may cause injury to people or damage structures below such as a glass conservatory.
High level gutter Low level gutter
High level gutter Low level gutter

The correct position and height of the gutter needs to be carefully determined, for example, whilst a lower level fitted gutter is less susceptible to sliding snow, it could result in wind driven rainwater going between the back of the gutter/roofline which can lead to water damage to the building fabric.

A gutter fitted at a higher level will alleviate this problem.

Each option has its benefits and drawbacks and more often than not the building design, gutter type and fixing will dictate how the gutter should be installed. Architects, installers and building owners should discuss the options available and ensure that all parties agree on the best possible solution for the site location, its potential for snow against the severity of exposure to driving rain.

Further information

Find out more by reading MGMA’s Eaves Gutter Installation Recommendations

Also read How to prevent damage by heavy, heavy snow

Although most people park their cars and vans on the road, occasionally we have to deal with an unexpected guest who arrives in their vehicle through the wall. 

When this happens it’s usually Building Control who’ll visit the site following a call from the emergency services to assess the structural implications that have been created. (The incident above was dealt with by one of our Central Bedfordshire team members - no one was injured, thankfully!) 

Building Control teams around the country have delegated powers under section 77 of the Building Act to deal with dangerous structures and, as in this instance, section 78 – Emergency Dangerous Structures.

This call can be at any time of day or night and while more common than you might think, it’s unusual to have two incidents like this within the same month.

You may have read the articles in the press or seen similar ones where it just states ‘a structural engineer’ or ‘a council officer’ attended the site.

In reality it’s Building Control who'll take the decision on whether it’s safe for the fire service to go into the building, whether the vehicle can be removed safely, what needs to be done to stabilise the building and arrange for this to be carried out so that they can leave the site safe having removed the danger. 

Often the residents need alternative accommodation, the building needs to be left secure and watertight, remedial work requires supervision and in some cases legal enforcement needs to be considered separately to any criminal investigation by the police.

This can sometimes take months to resolve before residents can return to their properties.

What do we do when we’re confronted with a dangerous structure like this? 

Well often it’s a deep breath first and then work through issues like isolation of gas, water and electric supplies, assessment of structural walls and damaged lintels, direction of supported floors and loads.

Work can then begin with the fire service to safely clear areas to allow temporary props to be installed to prevent further collapse. Once done the vehicle can be carefully removed to permit any additional propping and security hoarding to be installed.

Decisions are then made around how best to repair the building.

This part of Building Control's work can be complicated, dangerous and decisions need to be taken quickly to ensure conditions don’t get any worse.

So well done to the two building control teams involved in the photos, and the next time you see a similar photo in the newspapers spare a thought for the dedicated LABC officers out there helping to keep you safe.

View some of the dangerous structures our Building Control teams have dealt with.

Featured blog articles

Also read Builders and property owners feel the pinch and Fire doors in the dock

Published October 2017

The government’s new target of a quarter of a million new homes a year may well be needed - but will it create problems later on down the line? Making sure that housing is built well, and to a good enough standard is high on our agenda - it is also key to ensuring that the nation is housed in homes that maintain their value and last.

In this article LABC CEO Paul Everall talks about the ways that Building Control already ensures quality in house building, however he also talks about its limits and how he hopes recommendations from the All-Party Parliamentary Group for Excellence in the Built Environment  will be built on to ensure quality in the future.  Read more here.

You may have come across a recent BBC news item about a house collapse in London following basement renovation work. 

The property was thought to be worth in the region of £1 million and collapsed in the early hours of 3 April 2017.

Basement collapse in Kingston, London - picture from Kingston Building Control team(Picture on the left courtesy of the Kingston building control team.)

A building regulations application had only been submitted a few days previously and the building control team had not been given the opportunity to offer guidance or approval to this complex area of work.

Sadly this is not the first house collapse incident and it won’t be the last.

A similar house collapse at a property in Barnes, South West London in 2015 also followed basement excavation work, and in 2012 a property in Finchley, also undergoing a basement extension, collapsed with the owners only escaping serious injury by minutes.

Whilst this is the worst case scenario, other issues like cracking and misalignment of doors and windows due to minor subsidence can be frustrating.

As popularity in basement conversions continues to increase, the importance of using a competent builder following an approved sequence of works is critical.

Undermining an existing structure requires careful consideration and planning to ensure that the loads carried continue to be fully supported and transferred back to the ground correctly.

Help is at hand: ASUC

The Association of Specialist Underpinning Contractors (ASUC) offer access, guidance and insurance backed guarantees to accredited members.​ It is an independent trade association originally formed by a number of leading contractors to promote professional and technical competence within the subsidence industry.

Membership has now been extended to include a comprehensive range of specialist domestic services in underpinning and subsidence repair techniques, engineered foundation solutions and retrofit basement construction. 

View and download their Scheme Guarantees leaflet:

Further information

LABC in collaboration with LABC Warranty have put together a technical guide on basement design. View and download Better basements: design and construction technical guide.

Lath and plaster ceiling
Most pre-1930s houses will have traditional lath and plaster ceilings. Picture courtesy of Malone Associates Ltd

What is lath and plaster?

Laths are thin strips of wood (around 25-38mm wide and 3-8mm thick) spaced around 5mm apart and nailed to the ceiling joists above. Plaster was then applied to the underside of the laths, held in place by being squeezed through the gaps to create a ‘key’ or lug.

The plaster was usually made from lime mixed with sand and cement and included horse hair to act as a natural reinforcement and effective bonding key. The lime improves workability and breathability of the plaster. It was usually applied in two or three layers to a thickness of around 25mm. 

Interested? Read some more "My dad told me about them!" articles

How to check for lath and plaster

In older properties you can check the type of ceiling by looking under the loft insulation, or lifting a bedroom floorboard. If there are lots of small timber laths with creamy lugs of plaster in between, the ceiling is original.

The pros and cons

Plaster is brittle by nature and will crack at its weakest point under vibration or through water ingress. This weak point is usually at the lugs that wrap around the laths.  If this spreads across the ceiling even the horsehair can’t support the weight and the ceiling, or sections of it, will sag and then may collapse. Where sagging is evident the ceiling will move if gently pushed or make a hollow sound if tapped. Sometimes this failure can be disastrous, the collapse at the Apollo theatre in 2014 injuring 88 people during a performance was caused by water ingress weakening the lath and plaster ceiling.

However there are some good reasons for keeping an original lath and plaster ceiling. Aside from the features of an historic interior it has better soundproofing and insulating qualities than modern plasterboard. The mess associated with their removal, particularly over bedrooms with the debris found if loft spaces above will also make many think twice. Despite some being quick to condemn cracks or bulges they can usually be repaired for a fraction of the cost of replacement.

Irregular-shaped cracking, significant bulging or unevenness are more serious signs. Unless you can address the cause of the cracking there’s little point replastering because it may just crack again. Today's plasterboards have removed this problem although it’s still possible to get hairline cracking along board edges and blistering where screws haven’t been screwed in deep enough. 

There is also a tendency to take a short cut and overboard, leaving the existing ceiling in place. 

If this is being considered then you may need to check with an engineer to ensure the floor or ceiling joists are capable of carrying the additional load. Lath and plaster ceilings weigh around 0.5kN/m2 and plasterboard 0.15kN/m2. The screws used also need to be suitable and in sufficient number to take the additional weight.


Read some more "My dad told me about them!" articles

One of our surveyors came across this stairway on site recently.

Problem stair treads - these treads get deeper the higher up you go

Spotted the problem yet?

It's not an optical illusion, the stair treads increase in depth (the going) as you reach the top of the flight. 

Some might not view this as a problem. What's wrong with being able to fit your whole foot on the tread anyway?  

The issue isn't the walking up - it's when you come down...

The potential for injury  

For anyone unsteady on their feet or partially sighted, the change to a thinner step may cause them to lose balance and fall.

The higher up the flight, the greater risk of serious injury. 

That’s why you also need a full width landing at the top and bottom of a flight and can only have a door swing reducing the landing to 400mm clearance at the bottom (dwellings only). 

It is also the only part of the building regulations where a head height is stipulated for domestic properties.

The 2m head height (reduced to 1.9m for loft conversions) is to prevent hitting your head at the top of the stair or on the bulkhead, and falling.  

The solution

In this instance it was a concrete stair and relatively easy to overcome. 

Packing pieces were used to reduce the tread depth to a consistent going with the rest of the stairs and this also gave a larger landing at the top. Depending on the type of building, the going can range from 220mm to 400mm, but the golden rule is that twice the rise plus the going must always be between 550mm and 700mm. 

So for a 42 degree pitch private stair with a going of 250mm the rise must be between 150mm and 225mm.

Need to install a timber staircase properly? Read this.


Masonry is one of the oldest, most established building techniques, but its strength lies in the correct use of mortar, which plays a vital role. There are several things you need to do such as selecting mortar according to exposure conditions and chosen brick and blockwork properties. You also need to allow for movement, particularly when mortar strength is required for structural reasons.

Here’s a quick guide to the dos and don’ts of using mortar.

Mortar Dos and Don'ts


  • Don’t mix mortar when the air temperature is at or below 2 degrees and falling.
  • Don’t use sand or semi-finished mortar containing ice particles.
  • Don’t lay mortar on frozen surfaces.
  • Don’t add calcium chloride (accelerator for concrete curing), ethylene glycol (antifreeze), washing up liquid or mixtures containing these materials to protect against freezing or for any other purpose.
  • Don’t use air, entraining or other admixtures unless specified by the designer and/or manufacturer’s recommendations.
  • Don’t rely on volumes by the shovel as you might end up with inconsistent mix proportions and variations between batches that could affect strength, durability and colour.
  • Don’t knock up mortar when it has begun to set.


  • Use suitable waterproofing to protect newly built work from rain and frost.
  • Use the ‘wetting method’ on highly absorbent clay bricks to reduce their suction in hot weather.
  • Use a carefully selected prescription mix and a suitable mechanical mixer for site-batched mortar mixing.
  • Add plasticisers and other additives to the mortar mix to improve workability, but only if needed.
  • Use only products specifically designed as a mortar additive.
  • Use pre-mixed or factory-made mortar to ensure consistency throughout.

For more information refer to the LABC Warranty Technical Manual.

The next generation of engineered first floor joists offers greater spans and easier fitting of services. While hours can be saved removing the need for notching of pipework and drilling for cables, the floor joists still need careful attention to ensure they work correctly and as they are designed.

The posi-joists in this image are designed so that the top chord transmits all the weight. That is why there’s a gap where the bottom chords to the left are not in contact with the trimmer beam.

The problem with this floor joist image

The gap is too big! It should be a maximum of 6mm and if a stud wall is to be built beneath, there should also be a plasterboard noggin to prevent cracking at the junction. There should also be noggins between the top chords to prevent movement.

The joists to the right of the trimmer correctly have a timber fillet at the point at which they sit on the wall to stiffen the joist through its depth. But they should really be seated on a timber batten rather than the blockwork.

The cantilevered ends should be fixed to the trimmer beam with joist hangers to remove any bounce in the floor to prevent any cracking of the first floor finishes.

This will also minimise creaking, which is one of the biggest frustrations for new house owners.

Further information

Found this interesting? Try How to build level floors and browse our How to get it right articles

Published August 2016

With the UK’s decision to leave the European Community, there will be a tendency to focus on that alone and forget about what else this country needs to do. There may be calls to reduce regulation in order to stimulate house building if that is seen to be in decline. That would be short-sighted in the extreme.

In an ideal world we would not need Building Regulations to control people building new homes or improving existing ones. Everyone would work to high standards without this. However, this is clearly not the case and we continue to need Building Regulations to set minimum standards to which all must conform.

Building regulations and energy efficiency

This is particularly true in areas of energy efficiency. People improving and extending their home may well focus on providing a new bathroom or kitchen rather than ensuring what is built does not leak energy. The requirements in Part L of the Building Regulations in England and Wales ensure that adequate insulation is provided. Over the last 10 years Part L has seen more changes than any other Part of the Regulations, and LABC has worked hard with bodies like the Zero Carbon Hub to try and ensure that these changes are reasonable and practicable. Insulation manufacturers have played an important role in advising what can be achieved, and helping deal with issues like thermal bridging – where LABC has developed Registered Details to help builders.

Regulations in themselves are of no use unless they are properly enforced by building control bodies. Here local authorities are in competition with private sector bodies, and one of the risks of such a system is that price competition leads to lower numbers of site inspections and a greater risk of defects being missed.

Raising standards in local authority building control

LABC, as the representative body for the building control teams in local authorities in England and Wales, gives a high priority to encouraging our members to perform to high standards, and we have a number of initiatives going on at the present time to try and raise standards still further and to ensure consistency between councils.

LABC is proud to be a member of the NHIC as we have shared aims in trying to improve the quality of the existing housing stock. The impact of global warming means that we must do all we can to reduce carbon emissions from buildings, and working with insulation manufacturers is an important part of achieving this.

This article originally appeared on the NHIC website.

Levelling floors seems like a straightforward job, but it’s often complicated.

Shrinkage, poor workmanship, deflection and the type of materials used can all lead to an out of level floor - and worse, you’re likely to only find out after the job’s finished!

So, how much deflection is acceptable and how do you make your floors as level as possible? According to the LABC Warranty Technical Manual, floors up to 6m across can be a maximum of 4mm out of level per metre, and a maximum of 25mm overall for larger lengths.

That’s a 1:240 gradient, and whilst the telly might not roll towards the middle of the floor, it’s still something that can make a real difference to the finished job.

This is further complicated by the fact that a timber floor joist, for example, can be designed to be within permissible deflection parameters under British Standard or Euro code, but may still exceed the maximum out of level requirement set out in the warranty manual. As such care is needed, and the carpenter's adage - measure twice, cut once - should always be considered.

To comply with LABC Warranty requirements for new housing you have to stick to the tolerances in the manual - but there’s no real excuse not to apply this to domestic work as well.

Tips for getting a level floor

  • Shrinkage of timber floors and staircases is a natural occurrence when drying out, which could lead to squeaking as materials move against each other. Whilst it can’t be eliminated entirely, careful choice of timber and its storage and protection on site can minimise shrinkage.
  • When constructing upper floors any supporting walls or beams that are out of level will be reflected in the final floor, especially when it comes to timber floors. So checking these before the floor is put in position will save time and effort later on.
  • The effects of normal drying shrinkage on screeded floors could cause some fracturing.
  • The tolerance standards don’t just apply to timber floors - concrete beam and block floors should also meet this requirement.
  • To ensure the finished floor is level and within permissible tolerances, check, check and check again!

Read Chapter 1.4 of the LABC Warranty Technical Manual for more information on how to get it right on site.

Published July 2016