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How to Install Catnic Lintels

Catnic is one of the UK’s best-selling British lintel brands and brought the first steel lintels to the UK residential market in 1969. Light, and easy to handle, there are a few things to remember when you are installing Catnic lintels.

Whether you are a bricklayer, a site manager, or a homeowner, Wade has a wide range of Catnic steel cavity lintels to choose from.

Here’s our guide to Catnic Lintel installation.


Before You Get Started

Pre-start checks are the key to a good job. If you store your Catnic Lintel correctly, it should be in as good condition as when it first arrived on site. Put a straight-edge, or level on the lintel to see whether it has been bent out of shape or suffered other damage.

Do not use a lintel that is twisted, crushed, or otherwise showing signs of damage. Any obvious distortion could cause issues for the building further down the line.

Confirm the Specification

On a larger construction project, there will be several lintels in the store, so whether or not a storeman or another person is managing the stock, at the end of the day the person fitting the lintel is ultimately responsible.

Check the drawing and ensure the lintel selected is the right one for the job. You can use Catnic’s Lintel Selector to help you decide whether the product you have is the right one to install.

Catnic lintel load tables are available here in a comprehensive document that will give you the specific information required to help choose the right lintel for the job.

Confirm the Bearing

The lintel must have a minimum bearing of 150mm at each end, which means the lintel has to be at least 300mm longer than the structural opening over which it is set. If your structural opening for a doorway is set at 900mm, then your lintel needs to be at least 1200mm.

If the selected lintel is much larger than the structural opening don’t cut it down to size as this may void the warranty.

Confirm Site Readiness

Getting the site right is easier said than done sometimes, but the main thing to remember is that you should only place the lintel on full bricks or blocks. Cut bricks and blocks will not have the same force-bearing capability, so bear that in mind when setting out your masonry coursing.

When installing lintels with larger than normal loadbearing, it may require concrete padstones or other mitigating action. In case of very wide openings, or lintels supporting concrete floors or large roof structures, sign-off by a structural engineer is advisable.

Increased loadings may require a larger bearing area. Catnic and Wade can both help you with the specifications of lintels.


Top Tip:

Aim to get the walls up to the right height for lintels by the end of the week so they have time to cure over the weekend. By the time you return to site on Monday, they will be ready to progress to the next level.


catnic lintel install

Fitting the Lintel

Raise the inner and outer masonry leaves together to ensure that neither one is greener than the other when the time comes to progress to the next lift. Mortar will generally reach 60% of its compressive strength within 24 hours, and fully cure within 28 days.

The lintel should be laid upon a full mortar bed and levelled in both directions, across an opening and from front to back. You may require a separate damp proof course (DPC) in maritime, or exposed regions.

Next Steps

Set weep holes at 450mm centres with a minimum of two per opening. While the brickwork should not overhang by more than 25mm, the lintel should always extend beyond the window or door frame drip.

Once the lintel is built into three courses of brick and a single course of block, allow the mortar to cure before applying a load. Any floor joists or roof trusses must have at least the depth of one full block between them and the lintel flange.

Catnic Box Lintel Installation

When installing a single-skin lintel such as a Catnic box lintel in your internal wall construction, make certain that the wall is cured, that the specification and the bearing are correct, and that you use the same mortar so that expansion and contraction rates remain the same.

My Catnic Lintel’s Paint is Flaking or Scratched. Can I Still Use It?

Yes, you can. Clean off the lintel with detergent and use an abrasive brush to remove all loose material. When the lintel is dry patch prime, coat it with polyester or epoxy paint. Protect the lintel by fitting a cavity tray (DPC) and weep holes to remove any water.

In coastal areas consider fitting a cover over the lintel’s leading edge to protect it from the elements.

Wade is also an Approved UK Distributor for Stressline, Birtley and Naylor.


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