Shadow Boxes ... The wrong way and the right way

Right, I was asked to post more on Shadow Boxes and the way the issues presented themselves, and what could have been done to alleviate them. so I have done some hand drawings with my terrible handwriting added to the mix.  Hope you can read them and make things out.

Below we have a Shadow  Box and how it presents itself in a room when installed. Basically it does a cut out of a box into the base of the floor and uses the shadow created by the light hitting the top surface to make a dark shadow. They look extremely nice when installed and are commonly found in art galleries and the like as they compliment modern homes and décor quite well.

When I tested the house in question for my client, she complained that their house had gone from being a relatively warm house to downright cold after the builders had left. The intention was to add Kingspan internally on wooden battens that would be attached to the existing breeze block and as well to have a Shadow Box put in instead of skirting boards as they liked the look. Fair enough, they had the money to spend, they had the right decor, and they were looking to save money on energy costs with the added insulation.

What they ended up with was a gaping hole through to the cavity via the joists, chipboard, and any other penetrations running throughout the house. If you have ever read this blog, you know that air flow in the cavity, in the attic cold air space, and under the floors around the joists is expected and necessary to keep things right in your home.  The air barrier should be after the cavity and before the internal surface of the dwelling. This house went from having a decent air barrier to having an area equal roughly to the surface area of the shadow box multiplied by the total perimeter or the homes exterior and interior rooms.  Let's just say, it was impossible to get it up to 50 Pascals of pressure and that was with closing all the doors in the house! It was like every window in their house was open all the time even when every window was closed.

Anyway, here is a depiction of the top and side views of the installed walls:

As you can see the pathways for the air allowed anything in the cavity, or floor spaces to bring air into the home via the space left for the Shadow Box.

Two simple additions to this and a bit of tidier behind the scenes adjustments would have made this whole situation better.  As you can see in the drawing above from the side view, it is very rough where the floor coverings don't meet the exposed breeze block, and the underside of the wall allows the Kingspan and battens to be exposed.  In the following drawings you can see how this could have been alleviated by putting a simple parge coat over the exposed breeze block, foaming the join between the chipboard and the wall, and then putting an extra batten attached by an L bracket (or even screwed in if it would work) then applying  drywall to those surfaces prior to putting on the Kingspan and vertical drywall for the finish.

For more information or to book a test, call me on 01484 686649 or visit my website on http://www.hometestingyorkshire.co.uk/

I hope this helps,

Thanks,

Matt