MoE from 'town houses'

[Guest]

A colleague has just bought a 3 story town house with a floor more than 4.5m above ground level. Could one of you experts please interpret the AD 'B' requirements for me into English? The stairway is protected but there are no emergency egress windows. I also noted that AD'B' states that emergency egress windows should be 450mm high and 450mm wide whereas the relevant BS states a minimum size of 450mm X 850mm!

Any help to clarify this would be appreciated!

[wee brian]

Where you have a protected stair you dont need escape windows - other than for inner rooms.

Its not 450 by 450. Its a min 450 and a minimum area which I cant remember off the top of my head. This means that the opening is 450 by 700 and something.

The BS is out of date.

[Guest]

the protected staircase relies, of course on the occupants keeping the doors shut tight, even on hot sultry nights. Realistic, I don't think so! Never mind, the englishman's home is his castle. It reminds me of the fire resisting of dead-ends...it doesn't work, everyone knows it doesn't work...but lets keep pretending.

[logan_lewis]

Wee Brian is right and its 0.33m2 minimum area in addition to minimum of 450mm criteria.

[Guest]

I am finding it hard to understand this...Para 2.7 of AD'B' states that '...all habitable rooms in the upper storeys of a house served by only one stair should be provided with a window...which complies with para 2.11.

Para 2.11 then gives the requirements for emergency egress windows as discussed by others.

We then go on to 'additional provisions for houses with a floor above 4.5m' (emphasis on the word 'additional'). At para 2.13 the document requires that the house has either a protected stairway; or, top floor separated and given an alternative moe.

I interpret this to mean that all windows in habitable rooms on upper storeys should be emergency egress windows, plus, as the house has a floor over 4.5m. the 'additional' requirement (in this ccase protected stairway) is also needed.

Please let me know where I'm going wrong!

[logan_lewis]

If somebody used an egress window to escape from the top floor of, say, a 3 storey house they could cause themselves a serious injury, so more should be done to protect the internal means of escape - hence protected stair.

Therefore if the protected stair is sufficient for somebody from the top floor of, say, a 3 storey house, why is it not sufficient for the first floor?  This is to say, a protected stair may alleviate the need for egress windows.

I agree, the ad b wording doesn't make this clear.