Private Stairs

Stairway to heaven or footsteps fall?

One of the most common design queries we get relates to designing private staircases in flats so that robustdetails® can be used, thus avoiding the need for pre-completion testing (PCT). There are a number of ways to achieve this and these are just a couple of examples.

An example of the first way that works is the layout below. The stairwell is completely enclosed (i.e. with no under-stairs access), allowing the floor to be built into a cavity wall for its whole perimeter.

The resultant flanking junction around the stairwell can now be constructed in a very similar way to the external flanking junction for the concrete floors shown in the robustdetails® handbook, so it now meets the robustdetails® requirements.

The wall needs to resist noise transferring from the stairwell into the lower flat and so it needs to meet the relevant specifications, including finishes.

Another possible solution is to position the stairs on the outside of the building.

How not to meet robustdetails®

One of the most common ways of getting it wrong is by mixing stairwell wall construction. A typical layout of this type might look something like this:

With this situation, the sound from the upper flat can more easily flank into the stairwell – so now it’s down to the cavity wall to stop the sound getting into the flat below.

But unfortunately, the isolation provided by the cavity has been compromised by the floor, resulting in a flanking path straight through from the stairwell.

Flats with this design will be outside the scope of robustdetails® and would have to go through PCT.

So to keep your flat designs compliant with robustdetails®, stick to the principles of the first two designs. After all, two out of three ain’t bad.

If you have any techncial enquiries please do not hesitate to contact our technical team on 03300 882140 or email: technical@robustdetails.com

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