What is an acceptable DPC for cavity trays in cavity wall construction? NHBC Technical Guidance 6.1/38

Using the right grade of DPC for cavity trays is important in order achieve the NHBC Buildmark warranty.

On 11th November, the NHBC published technical guidance note to clarify what was already in the standards.

Here’s a brief summary of the guidance note and help on selecting the right product:

What DPC can’t I use as a cavity tray?

Polyethylene DPC made to BS 6515: 1984 (categorised as low-density polyethylene). This IS suitable for use as a DPC to prevent moisture rising from the ground but NOT as a cavity tray.

What DPC can I use as cavity tray?

The product selected must meet ALL of the following criteria:

Material: Flexible (plastic or rubber) DPC
Designed: To prevent the downward passage of water or moisture through the tray
Performance: Meets the requirements of BS EN 14909
Certification: Third-party certification that confirms their suitability for use as a cavity tray

That sounds expensive!

A high performance DPC can cost up to four times the price of a standard DPC. When comparing quotes, it’s useful to bear this in mind to ensure you’re receiving the right product for the application.

When does this guidance come into force?

Whilst this has been part of NHBC guidance for some time (Standards clause 6.1.17), on “all plots starting or at DPC level as at 1st January 2023, the use of appropriate flexible DPCs (as described above) will be required and use of low-density polyethylene DPC conforming only to BS 6515 will no longer be accepted.”

What’s the right product to select from Multifix?

We stock the Visqueen Zedex CPT high performance damp proof course as 20m length rolls in widths 100mm, 450mm & 600mm. We also carry a range of Brickwork sundries including pre-formed cavity trays for corners and ridges.

If you already have a Multifix account, roll your mouse over any of the product sizes or references above to see your rates.

How can I be sure this is the right product?

The products meet the requirements of BS EN 14909 and Visqueen carry third party accreditation specifying its use as a cavity tray, as per the NHBC technical guidance. Download BBA 94/3059 and their DoP here.

How do I open a Multifix account?

Click here to open an account.

Where can I find the full technical guidance note?

Technical guidance notes can be found on the NHBC website. Here’s a link to note 6.1/38

Article

How a speedy supplier can improve your supply chain

The famous saying “slow and steady wins the race” certainly is true in some aspects and when it comes to a project, you can’t rush quality. However, it doesn’t always apply. This is especially the case when you need service from your supplier quickly – be it getting a quote, making an order or receiving a delivery. In this article, we will explain just why speed from your supplier matters and how it can make your life a whole lot easier. More time to prioritise the things that matter With a speedy supplier, everything falls into place much easier. You aren’t spending your day waiting around for a quote, you aren’t falling behind schedule because your deliveries are late and you can order what you need within seconds. This allows you time to solve other issues and to focus on the things that really matter on your projects, whatever they may be. Irrespective of what project you’re working on, being efficient helps significantly and if you can find a way to ensure that with your supplier, it all helps. Speaking of help, what can Multifix do when it comes to speed? Speed is one of the things prioritise so much at Multifix – and especially prioritising it while not compromising on our reliability or quality of service as a result. For example, we’ve worked especially hard to be in a position where we can guarantee that you’ll have a quote back within half an hour. In addition, should you be on our customer portal, it’s possible to make an order within 30 seconds. Everything on the portal is aimed at your convenience and that includes speed. As for deliveries, 75% of our deliveries are on-site before 12pm midday. In some cases, we’ve been able to have goods ready before site work even starts. When it comes to making your life easier, these are things we’ve found really help. Rapid resolutions We know how much speed can make an impact on your lives and your work projects, so that is one that will always remain one of our core customer values. One aspect of our speedy service is our delivery though, which we are delighted to say has a 99.3% success rate. To find out exactly where we deliver to, click here.

Comparing two of the best PFP solutions for loft compartmentalisation issues

Picking passive fire protection products when fitting a loft is a big decision. The need for it is enormous, given that without it, the loft is left open above the party walls. This means that a fire could tear through the loft, so compartmentalisation is necessary. However, picking the right solution can be difficult. In the main though, there are two main PFP solutions for loft compartmentalisation issues. They are the Protecta 80mm FR board (or 80mm batt) loft space system and either the Rockwool or Firefly fire curtains and in this article, we will compare both. We will be honest and admit that we do stock the 80mm FR board, but we will still provide a balanced and objective comparison between all three products. By the end of the article, you’ll know the differences between the batt and the fire curtains and which one will be better for your project. What are the main differences between the batt and the fire curtains? The key difference to note is that both the Firefly and Rockwool fire curtains are two layers, whereas the 80mm bat is just one layer. However, both still have the EI60 fire-resistance classification rating, which means they can hold off fire for a minimum 60 minutes. The feel of both is very different, too. The fire curtain is an insulation-like material, while the 80mm bat is more of a board. Other than that, there’s not a great deal of difference between the products, although both have different pros and cons, which we’ll come on to. There’s also not a lot of difference cost-wise, so your choice will be based on what system is best for the situation at hand. Pros of the 80mm batt One of the biggest pros of the 80mm batt is the speed of installation. It is estimated that the time to install an 80mm batt is 25% faster than other types of products, which can help you save on labour costs. This is because there is only one layer to install as opposed to two, but you still get the EI60 fire rating with the one layer. It’s also more pleasant to work with, in the sense it isn’t itchy and is quite easy to get into a loft space. Also, loft compartmentalisation is a tested detail on the bat, which is something of an industry exclusive. For those unaware, a tested detail means that the product has specifically undergone testing for that scenario. An assessment detail is something that has been given afterwards but isn’t specifically for the task at hand. Pros of the fire curtains Both Firefly and Rockwool are big industry names, so you’re getting a trusted brand. The Firefly fire curtain is seen as the industry standard, while Rockwool’s name is synonymous with quality. The fire curtains are also very lightweight and both also have the EI60 fire rating, which matches the 80mm batt. They can also be integrated with fire alarms, which means they are only activated whenever a fire is detected. A barrier will then be made between the fire and the free space. Another pro of the fire curtains is that they are very adaptable, in that they can be cut-to-fit on-site to certain size requirements. This can be particularly useful if they need to be installed on a property with an unusual design. Cons of the 80mm batt While it’s worth noting that both the batt and the curtains have very few flaws, there are a few prominent ones for each that could sway your decision. The main one for the 80mm batt is that it hasn’t been tested with doors in it, which could be an issue if there’s a fire door present. In this situation, the batt can still be fitted, but the installer would need to fire-certify the door first. If time is of the essence, then this could be problematic. Cons of the fire curtains As for the fire curtains, the main cons come for those who are handling them. Like all insulation material, they are rather itchy if they encounter your skin and they are also difficult to physically carry. While the curtains themselves are rather lightweight, the massive rolls they come with are not. Bringing these into a loft space can be challenging for those lifting them. Finally, as the fire curtain is two layers, it takes longer to install compared to the batt. Both have the same EI60 rating, but one is much faster to install than the other. Choosing between the batt and the fire curtains Both are very good products in their own right and most importantly, both will get the job done of protecting those living with it installed. If you are installing in a loft that has a rather unique design or has a fire door, then the fire curtains will be the best choice. Your workers may have issues lugging the curtain into the loft space and getting itchy skin, but the result is hugely impressive. However, if you’re in a normal setting, where there are no unusual characteristics to the building framework, then you can go down a different route. That different route can save some time, while also ensuring the same level of fire safety is intact. As such, in those circumstances, the 80mm batt is a great option. It could also save you in labour costs, as you could install more at a faster rate, helping you speed up a project without compromising on safety. The Protecta 80mm batt is still a relatively new product on the market, so if you would like to speak to our expert team for more information, you can do so here.