Tag: defects

HPH318 : Do I need a structural warranty for my self build home? – with Jake Fitness
Jake Fitness of Self Build Zone explains what a structural warranty is, and why you might need one on your self build or renovation project.

Interview with Jake Fitness

Jake Fitness is a team leader at Self Build Zone, a provider of site insurance and structural warranties.

A structural warranty is a type of insurance policy

It can cover any new structural works you do on a project, whether it be a new build, renovation or extension.

It will be more costly to add on at the end

Jake stresses that the ideal time to start thinking about the structural warranty is when you have a pretty good idea of what your project will entail. This is for three reasons:
- To ensure that your building is acceptable to warranty providers
- To be able to factor it into your project budget
- Leaving it until the end will mean they charge a higher price, as the surveyor won’t have had full visibility of the build process.
“If you’re thinking about doing a project anytime soon, really make it one of the first things you do, because it’s more important than your kitchen, your doors and your windows and all of the nice looking fittings, because ultimately, it’s what’s going to pay you if there is something wrong with your build.”

Typically the price of a warranty is based on the size of the property, the frame construction type, and the build cost. The average warranty cost is between £2,500 and £4,000. This covers the full premium for the 10 years, plus all the site audit visits.

It isn’t a legal requirement

It is however likely to be a lender requirement if you’re looking to re-mortgage the property within that first 10 years, or if you are going to sell it during that time. You can still purchase a warranty at that time, but you will end up paying a far higher price for it.

It doesn’t hold anyone liable for the damage

The difference between a warranty and a standard contractor’s guarantee, is that you don’t have to hold anyone liable for the damage that has been caused. This is because rather than blame being placed on the architect or contractor for cracks etc, the warranty provider will conduct an independent survey to assess the damage and pay you for that loss. This can be beneficial if you’re looking to sustain the working relationship with the team in the future as you’re not trying to place blame on an individual or company that may not even be at fault.

Technical audit surveys are carried out

These repeat visits are similar to that carried out by a building control officer, but are purely from the viewpoint of whether there is likely to be a claim within the next 10 years. They are more comprehensive than whether they just meet building regulations, and on a new build would typically take place:
- when the foundations are fully excavated but before the concrete is poured
- at the damp proof course stage
- for brick and block it will be when you’re at first floor joists, or for timber frame and ICF it will be when the frame has been erected
“We’ll still carry on even when you’re at the weathertight level all the way up till completion, letting us know of any defects during the build, which, to be honest, most builders if they’ve built a small defect in then they’re probably going to not let you know about it. But we will stop the building in its tracks if we need to, just to make sure everything’s rectified and built to a very good standard.”

A structural warranty will cover defective design, workmanship and materials

This will be for a period of 10 years after completion.

An example of this could be the structural engineer not designing the foundations deep enough and the property subsides. Worst case scenario would be a claim for completing demolishing and rebuilding.

Other things that would be picked up could be things like a roof not being designed to take the full weight of solar panels, or poor mortar mixture being used that needs remedying.

Select a provider that has an A rating

Although the actual cover of the warranty is much the same for all providers, it is important to check that who is actually insuring and paying for the claims has an A rated backing. This relates to how financially stable they are, and how likely they are to still be around in 10 years time if you do need to make a claim.

Jake says an unrated insurer should be avoided as they don’t have evidence of their stability within the market.

He also recommends doing your due diligence by checking out blogs, reviews and testimonials to select your provider.

All construction types can be covered

Jake explains that Self Build Zone will cover all construction types, because each self build is so different. Rather than making blanket statements about the construction types they are able to rely on the auditing process from when they come out to do the inspections. This includes straw bale with thatched roof, and green oak frames.

Having been a warranty provider for over 20 years, Jake says that they are helped by being in the position of knowing what causes claims within the 10 year period, and the types of risks associated with each construction type.

A structural warranty is more comprehensive than alternatives

Contractors have a defects period where they will be responsible for all claims for the first two years following completion. That’s not something that you would typically have under a self build warranty though, as self build can relate to anything from full involvement by the contractor, right up to 100% of the work being done by the homeowner themself. If you do rely on a contractor’s guarantee and they go out of business within the following 10 years, you won’t have anyone to go back to for any of the defects that may arise.

Likewise, architect’s certificates (Professional Consultancy Certificates) are also sometimes available, but will only cover defective design, and not the workmanship or materials for the property. You would also have to prove that the architect was at fault, and are usually only valid for six years. In contrast, with the structural warranty, you don’t have to evidence the fault to any particular party to claim, and it would be provided for 10 years.

Another reason for having a structural warranty, is that sometimes local authorities may ask for one to show that your property is a self build and therefore exempt from paying a community infrastructure levy.

Find out more

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June 27, 2022
HPH269 : What is snagging? – with Chris Parsons
Chris Parsons returns to Ben Adam-Smith’s self build home after a year to look for defects. He explains what snagging is, how the list is compiled and how the rectification process works.

Interview with Chris Parsons

It has already been a year since Ben Adam-Smith completed his self build project. In that time, Chris Parsons has taken retirement from his architecture business, but still has a few outstanding projects to work on. But before he can entirely devote his time to his new interests there’s the matter of snagging to carry out on Ben’s home.

There are contractual obligations

The contract that Ben had with his builder stipulated a 12 month rectification period, whereby they would return to put right any defects of materials or workmanship that arose during that time.

As part of that contract Ben kept a financial retention to ensure that happens. Once the work has been finalised Chris can issue a certificate and the remainder of the money must be paid.

Normally if defects occur they can be left and dealt with together at the end of that period, but any that occur that prevent you from enjoying your property should be dealt with in a reasonable time, which is where a good working relationship with your contractor can be advantageous.

“All defects are inconvenient, but I don’t know anyone who can build absolutely perfectly, spot on, day one.”

The architect and residents may notice different defects

Having lived in the house for 12 months there are bound to be things that a resident would notice, which an architect coming to do a defects list may not. This is why Chris recommends keeping your own list, so that the architect can determine whether they are proper defects and if applicable add them to his list for the contractor. Likewise there will also be things that his professional eye would spot that may previously have gone unnoticed.

A water mark in the kitchen revealed a problem

The shower tray had dropped and caused the sealant to crack

Some shrinkage and movement is to be expected

Chris explains that shrinkage isn’t technically a defect, though a contractor would likely return to put it right anyway. When using some natural materials and any type of plastering process that involves putting in a lot of moisture there will be an amount of shrinkage.

There will also be some movement as the building settles into position. This may result in cracks on walls or gaps in sealants. Generally the plan to rectify it would involve some filling and redecoration, although this could amount to a considerable amount of work.

A window with several streaks on the central pane

The glass in most of the windows had to be replaced

Ben’s snagging list

Ben is thankful that there are only a dozen or so items on his snagging list, including:
- They are aware of some sound connection in the MVHR from the en-suite down into the kitchen, so this is something that Chris will have to check on the drawings to try and work out what could be the cause.
- The biggest issue they’ve had has been the glazing. There were defects in the glass panels which was down to a manufacturing error, but the supplier dealt with it effectively and these were replaced.
- There have been some minor shrinkage cracks, but also one around the window reveals where the angle bead has moved which will need to be addressed.
- The shower tray has dropped a little which may be the cause of a small leak down into the kitchen where the silicone has pulled away a fraction.
- There is some creaking in the upstairs floorboards, which Chris thinks could be down to natural movement over time and changing during the seasons.
Occupants need to learn how to use their houses

During the hottest period of the summer Ben’s house did very briefly reach 28 degrees, but this hasn’t been a cause for concern. Chris says that some houses will naturally be easier to keep cool than others, based on their orientation and site constraints, so at the design stage they will try to mitigate what will likely cause the overheating. He says occupants should also learn the techniques for cooling their house.

“As designers we need to be looking carefully to try to make sure that our houses can stay cool because we’re going to get more and more of those heatwaves. We need to understand that. We need to make sure that people know how to use their houses, but most of all we need to make sure that designers know what they’re doing. This is not true of the Passivhaus fraternity but I’m not convinced that many of our house designers fully appreciate that problem.”

There can be a fine line between defects, and wear and tear

An architect in this situation can take on the role of adjudicator. Chris calls this client management, where an occupant might have something on their own snagging list that actually Chris would put down to being a matter of wear and tear, rather than a contractual defect. It’s Chris’ job to determine what is fair to add to the list that is presented to the contractor.

Not all defects will be detected within the 12 months

Even after the 12 month period there may continue to be some movement and shrinkage, however this will then fall outside the responsibility of the contractor.

There are other defects that the contractor can continue to be held liable for even after this time. These are called latent defects, which might be a defect in materials or workmanship. Even if it’s several years later they can still have some responsibility to come back and put it right. Chris explains that there is a technical legal limit to it, but it’s basically at the point at which it should reasonably have been discovered.

Later alterations are your responsibility

Ben is thinking about adding another external water tap. Because the water supply will be inside the thermal envelope Chris advises caution when drilling a hole through the building fabric and making sure a grommet is put on to avoid too much air leakage.

“But it’s something that is completely down to you to organise. There is no responsibility left for any of the people that were involved in the build contract to deal with your alterations, extensions, or anything else you want to do, other than making sure that you’ve got all the information you need to be able to do it properly.”

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October 30, 2019
HPH052 : Identifying Construction Defects by Using Thermal Imaging Cameras – with Lisa Ann Pasquale from Six Cylinder Limited
Lisa Ann Pasquale from Six Cylinder Limited explains what thermal imaging is and how it can be used in quality assuring the construction of low energy buildings.

Interview with Lisa Ann Pasquale

Lisa Ann Pasquale is an architect by training but after several years supervising construction works in Boston, USA, she took a masters in building physics from the Architectural Association.

With practical experience under her belt she frequently found herself shooting holes in her professor’s theories about perfect construction! It was at this point he suggested that she might be suited to becoming a post occupancy building performance evaluator and that’s exactly what she did.

Lisa now runs Six Cylinder Limited.

Thermal Imaging Allows Us to See Differences in Temperature

While part of the electromagnetic spectrum is visible to the human eye (visible radiation – light) there is a lot more that we do not see.

Thermal imaging allows us to look at infrared radiation, which is a slightly different wavelength, and deals with the heat of objects.

If you point a thermal imaging camera at your hob when you’ve just cooked a meal, you’ll see it glowing red. Likewise if you open your fridge it’ll be black or blue. So it allows us to see differences in thermal temperatures.

When it Comes to Buildings, Thermal Imaging Helps Identify Anomalies

Thermal anomalies are significant differences in temperature which wouldn’t normally be expected.

For example, you would expect a wall to have a fairly consistent temperature from top to bottom and thus it would be the same colour on the thermal image.

This image below shows air infiltration where some sealing tape was accidentally missed around a door and window. This caused large amounts of cold air (the black patches) to flow into the room, through the interior wooden wall cladding. This was noticed using thermal imaging in the later stages of construction and corrected by the builder before the building was handed over to the client.

Rainscreens Can Mask the Defects

In certain situations it may be difficult to get meaningful thermal images.

Rainscreens, which are often cladding that is a certain distance away from the rest of the building fabric, make it very difficult to see if there’s a problem (from the outside). However, the defect would still show up on the interior pictures.

This is one of the reasons why thermal imaging should be carried out on interior surfaces as well as exterior surfaces.

Depending on the Project, Thermal Imaging is Useful at Different Times

Ahead of a retrofit it makes a lot of sense to carry out a thermal imaging survey. This is because you want to be certain you know what is going on and that you’re not about to insulate damp building fabric.

In a new build, thermal imaging is unlikely to take place until the heating system is commissioned.

Most Defects During Construction are Accidental

Lisa says it’s relatively rare that a building defect is down to blatant negligence on the part of a contractor. More often than not a tradesperson has forgotten to do something and just needs to go back and fix it.

An example of this might be an electrician who scoops out some insulation to install a socket and then just slaps a plate over it without putting some insulation back. Therefore a cold spot would show up on the thermal image.

Poor Design Can Lead to More Significant Issues

Detailing is very important to get right. If it’s not done correctly, heat can be conducted directly from inside to outside. This also increases the risk of condensation (where warm, moist air will come into contact with a colder surface).

Beware of the ‘Drive-by’ Survey!

When it comes to organising a thermal imaging survey Lisa says: “It’s not a particularly well-established practice. It’s not super common to do it. It’s becoming more common which is really positive.”

Even people who are certified to do this as a service may not be a good choice. This is because they are not invested in the process and are just there to take a few snaps. You want someone who takes the time to understand what’s going on and looks for specific details that might be an issue.

The Right Conditions are Necessary to Achieve a Meaningful Survey

The weather conditions need to be right to conduct a thermal imaging survey. They are mostly done in winter and on overcast days. If the sun is out it will heat up the external walls and if it’s rainy or windy there will also be issues.

Doing it at night or early in the morning can be an option, too, because this is about the infrared spectrum and not the visible light spectrum.

At Least a 10-Degree Temperature Differential is Necessary

The temperature inside needs to be at least 10 degrees hotter than outside and this is achieved by artificially boosting the temperatures by running the heating system for a few hours.

Before the photos are taken the radiators are allowed to cool (so they don’t show up in the pictures!).

The Images Must be Calibrated Properly

It’s important to make sure that the camera is calibrated for the emissivity of the material that’s being measured.

While bricks, woods and concretes are all in a similar range other materials, such as zinc, are not. Therefore you’ll get a false reading unless the camera is re-calibrated.

Thermal Imaging Provides a Quality Assurance Process

Lisa tells a story of how she spotted a serious building defect when just messing about with a thermal imaging camera on-site at a children’s centre.

After hearing about it the contractor quickly realised that a sloppy tradesperson had slapped up some trim and cladding without putting in any sealing tape around the windows and doors, etc.

The issue was quickly fixed. If it hadn’t been remedied the client would probably have ended up with mould, condensation and rot on the inside of building.

Interpreting Images Requires Expertise

Thermal imaging is a great tool but it’s important not to overestimate what it can do.

These photos will be no good without a person who can interpret what is going on from the image and suggest the best course of action.

The example below shows the outside of a building on a cold morning (pre-dawn). The bright red/yellow colour indicates that heat is escaping the building via a detail around a large beam. This is creating a thermal bridge at the top of a glazed curtain wall, allowing heat to move from the inside of the building to outside.”

Ask Your Architect a Few Questions about Thermal Imaging

If you are building a low energy house then thermal imaging should form part of the quality assurance process.

So when you are hiring an architect, it is worth seeing if they are familiar with it.

Lisa says: “If this is something that is completely foreign to an architect I would be a little bit hesitant about working with them to design a low energy building.”

A sample report

Certain Information Should be Included in a Report
- The day and time that photos were taken
- The emissivity of the target surface
- The approximate distance that the camera was looking. Ideally all images should be taken at right-angles to what’s being photographed (so that the whole image is at the same distance from the lens), but that is not always possible with building details.
- The building plan or relevant detail is often helpful to have alongside the images so that you can orient the images or see which detail caused an issue.
- The reports should have a covering page noting the time/day of the survey, the site weather conditions (wet, snow, overcast sky, sunny,wind speeds, etc) and the conditions for the previous 4-6 hours and matching visual and thermal images, amongst other details.
Find Out More

Transcript

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Our Question for the Comments Section

How has thermal imaging helped your project?

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May 7, 2014