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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Fire Safety => Topic started by: Paul2886 on May 17, 2008, 08:07:29 PM
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Whats's the answer?
The scenario: A care home has just undergone a total redecoration program from top to bottom. Along comes me to undergo a FRA. Quite happy with the detection system, (almost an L1) happy about the new FD30s doors, if fact quite content with most aspects except all the walls and ceilings are lathe and plaster. It is my belief that these offer very little FR to the escape routes and between storeys.
Your opinions would be much appreciated here.
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Have a look at Envirograf they do a paper covering for lath and plaster walls and ceilings that can give up to 60 minutes fire resistance plus many other products that might help.
http://www.envirograf.com/main/products.html
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Have a look at Envirograf they do a paper covering for lath and plaster walls and ceilings that can give up to 60 minutes fire resistance plus many other products that might help.
http://www.envirograf.com/main/products.html
Thanks for the info Colonel but the problem will be that its all just been decorated. Unfortunately the standard of walls and ceilings was always seen as ok by the FA when they used to do the annual inspections in this care home. Then along comes Mr misery guts here and who says different. Do others face these problems or is it just me.
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One of our local authority's take on this is "if the lathe and plaster is in good condition, with no cracks then half hour resistance is assumed".
The above wording is from memory, not word for word.
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I appreciate your building probably isn't old enough to be considered a heritage building, but lath and plaster walls have been round a very long time. A look at www.english-heritage.org.uk may provide you with some useful information, or possibly www.bre.co.uk (Building Research Ltd.).
I recall from my experiences that ceilings, rather than the walls, are more likely to give way under fire conditions. Even more damage can occur to the plaster, wall or ceiling, when the fire is being extinguished.
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Hi Paul
Yes its sometimes very difficult to have to break such bad news to people who have genuinely tried over the the years to do everything required of them and have been the victims of poor service and bad advice.
Couple of observations and please forgive me if I am going over old ground.
During the early years of the care homes boom in the early 80s many old buildings were converted, many of which had decorative lath and plaster ceilings - and the draft guide was looking for an hours fire resistance between floors. A number of proprietary methods were devised to improve the fire resistance from above subject to appropriate specifications. Two that I recall involved lifting some floorboards in the room above, nailing chicken wire between the joists and infilling between the joists with mineral fibre or Tilcon made a lightweight cement product.
As far as lath and plaster is concerned the thickness of the plaster and its condition are paramount to its fire resistance. If I recall tests for English Heritage concluded that if there was a covering of at least 12.5mm over the laths, if this was consistent and free from cracks and damage then it may have a nominal half hour standard. I have had a look at a lot of ceilings and a consistent plaster thickness of 12.5mm is very rare in my experience- usually areas are much thinner than this.
As far as walls are concerned then fire resistance properties are unpredictable and through the laths can be ignited through conducted heat from a not too significant fire in the room- this leads to very rapid uncontrolled fire spread. I learned this the hard way on a recall to a fire many years ago but thats another story.
So I guess if you do have this problem and if the ceilings have not been upgraded invisibly (Heres hoping) I would suggest a 5 year plan - review and identify the most critical areas of the building and incorporate a range of solutions, focussing on critical areas to life safety and using a variety of techniques as appropriate to the circumstances.
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Thank you all for your replies its appreciated.
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With AFDat almost(?) L1, and a good management practice, could be considered a positive offset, and if walls and ceilings are well maintained, not too much a problem.
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The only problem I see if the evacuation strategy. If it is simultaneous or PHE you may get away with it but defend in place may be a stretch.
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Building research establishement digest 208 - Lath and plaster in good condition will provide a notional fire resistance of 20 minutes.
(most lath and plaster now over 50 years old - good condition?).
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Much of the condition issue relates to the way the lathes are fixed back to the structure.
The little nails that were used 50 odd years ago tend to rust and get loose in the holes.
Saying that - there's plenty of plasterboard that hasn't been fixed properly....
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is this lathe and plaster in Scotland?
Where the lathes are held off the cold stone external wall wall by horizontal 'pugging straps' to create an airspace beween the lathe and the outside wall. An early form of cavity wall creation to stop the cold creeping though. But if a fire penetrates the plaster then the lathe, the vertical spread via the airspace can be remarkable.