This following gives you an overview of all the components you’ll need to successfully install one of our external wall systems.
We have two systems for external wall insulation.
One is the UdiFRONT system which is perfect for flat surfaces and timber frames. The second is the UdiRECO system which is designed for uneven surfaces such as rendered or historic walls and also for uneven, part timbered surfaces.
Thickness of boardIf you’re choosing the UdiFRONT system you’ll need to decide which thickness of UdiUnger-Diffutherm boards you’ll need to use, this will depend on your target U-value. We recommend you allow 5-10% waste and assume that each board is roughly 1m2. If you need to go thicker than 120mm then add a layer of UdiTHERM SK to the build-up which is fixed first.
Number and type of fixingsOnce you’ve calculated how many boards you need, you’ll need to calculate the number of fixings required. If you’re fixing back to masonry you need the UdiASSEMBLY Masonry fixings for historic or soft substrates. High density substrates hold fixings better and so the UdiASSEMBLY Hammer Fixings can be used or if on to timber then use the UdiASSEMBLY Timber fixings. On masonry you’ll need 9 fixings per full board and on timber you’ll need 8-9 per board, depending on the stud centres.
Thickness of board
If you’re choosing the UdiRECO system choose the thickness that meets your U-value target. Its also worth checking the level of variation that you get in the surface of the wall as each board can only accommodate a maximum of 20% of it’s thickness. The boards go up to 200mm so will cope with 40mm variation in the surface and take your U-values down to 0.18 W/m2K. We recommend you allow 5-10% waste and assume that each board is roughly 1m2.
Number and type of fixings
Once you’ve calculated how many boards you need you’ll need to calculate the number of fixings required. If you’re fixing back to masonry you need the UdiASSEMBLY Masonry fixings or if on to timber then use the UdiASSEMBLY Timber fixings. On masonry you’ll need 8 fixings per full board and on part timbered surfaces you’ll need 8-9 per board. Call us if you have any questions.
Thermal bridging and openings
All the openings in the facades of both of the above systems need to lined with the UdiUnger-Diffutherm reveal boards. These help form neat reveals and also reduce thermal bridging around the openings. You’ll need to use these boards to line the heads and sides of all openings but the cills don’t generally need it. Remember to include the full thickness of the insulation and the depth of the recess of the window. The reveal boards are 1300 x 800mm and are glued in place with the UdiSPECIAL ADHESIVE. This adhesive is also required for all of the external corners in both systems.
Next you’ll need to look at all of the beads and trims. Along the base of the wall you may need to use the UdiBASE plinth starter track and UdiBASE plinth edging strip to provide a robust base detail to the system. Alternatively you can use polystyrene insulation, where it is less than 300mm above ground level.
Beads and trims
Around all of the openings you’ll need the UdiREINFORCEMENT render edging strip, allow for the same linear meterage as the reveal boards above. UdiREINFORCEMENT corner protection profiles are needed for the whole perimeter of windows, the heads and sides of doors and also for any external corners. Allow four of the UdiREINFORCEMENT corner strengthening mesh for each window and two for each door. Every opening will need two of the UdiREINFORCEMENT 3D corner reinforcement pieces.
And finally, rendering
Finally you’ll need the render to finish the systems off. The UdiFOUNDATION COAT render is applied at 5mm thickness with a half-round knotched trowel with the UdiREINFORCEMENT Mesh bedded in it. Each bag should cover at leat 3.5m2 at this thickness and the product is used from the ground up to the very top of the system. Where the render is less than 300mm below ground then it will need the UdiBASE plinth slurry to prevent moisture from penetrating the system. Next, the UdiPERL primer is applied with a roller, followed by the UdiPERL finish render.
If you have any questions, please contact us.
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