Retro fitted strips / seals

[jasper]

Just looking for backup on my thoughts on retro fitted strips / seals. I have a property with intumescent strips only fitted to the door casings, rather than removing and fitting combined strips / seals the contractor has removed the doors routered them out and fitted combined units to the doors therefore giving two lots of intumescent seals facing each other.
I am sure this is non compliant as the intumescent strips once activated would push against each other resulting in excessive pressure, also the only way this can be compliant is where a door and casing has been subjected to a furnace test.
I know the contractor is going to argue this but I am looking for written back up i.e. from TRADA or BWF etc.

[kurnal]

I don't think you will find definitive advice from the official bodies Jasper. I hope you do but I predict  their line will be that upgrades of existing door sets  are untested and therefore a step in the dark.

Presumably this came about as part of a recommended upgrade to install smoke seals where previously none existed. Whilst perfectly effective retro fit smoke seals are available that fit in the frame ( eg bat wings) presumably the contractor has just gone out to the builders merchant and bought standard combined seals.

I believe best practice advice supported by ASDMA et al in such a case is that if the FD30 door remains a good close fit in its frame and closes effectively then it is still fit for purpose. They will say that the consequence of carrying out upgrades retrospectively is completely untested and unpredictable. However such an approach will not meet the approval of many enforcers in the industry, or many fire risk assessors. I think there is a specific determination on this on the HMG website.

On the other hand there are proprietary seals available on the market and some have specific fire test certificates and some of these claim to be able to overcome many of the problems we assessors encounter in the real world, including compensation for excessive door / frame gaps. You and I know only too well that sometimes we assessors have to make judgements in the field and may use such products, just as we make compromises in heritage buildings, always taking into account the full circumstances of the case.

As for the double seals I wager that nobody will have seen or tested the consequences of this. So much will depend on the fire, the type of seal and where they sit in relation to each other. You could speculate that 25mm doorstops will exacerbate the problem- but speculation is all it would be.

I will hold my hand up to similar upgrades in the past, but usually I have recommended that the old seal be removed and the gap in filled with a hardwood fillet though workmanship is critical. I know that this will attract concern from the door industry but remember sometimes this work has been a requirement of an enforcement notice.

[jasper]

Many thanks for your reply Kurnal, your views are the same as mine. However the contractor is a large national and if this on my snagging list they will go to town on me as means of not doing any remedial works. Could it be an option to bring in the local FRS and see what their opinion is?

[Fishy]

I would envisage the same as Kurnal re: the response from TRADA etc - "Do what ever the test evidence says" (even the latest version of BS 8214 says much the same, rather than having all the detail about what "good" or "bad" looks like that previous versions had).

To get very boring and geeky... as you say it isn't good practice to install intumescent seals opposite each other in the leaf and in the frame and you could reduce the performance of the doorset if you did, due to excessive pressure build-up when they activate.  Potentially a significant problem with graphite-based seals; less so with sodium silicate or mono-ammonium phosphate. Double-leaf doorsets more vulnerable than single leaf.  I'd suggest that it isn't a huge fire safety issue in practice, but if someone has paid to have this work done then the people doing it ought to have been competent to know what best practice is, and they should have done it right!  There is also a liability issue, if the worst came to the worst and there were a fire.

Kurnal's advice is sound - easy fix is to replace the frame seals with tightly-fitted hardwood fillets adhered with a thermoset adhesive (e.g. epoxy resin).  I'm also assuming that we're discussing FD30 doorsets - if FD60s then you really ought not to vary from whatever was tested (& upgrading existing timber doorsets to FD60 isn't usually practical).

[Davo]

jasper

Although I am retired, I do remember there are 3 types of IS, each with differing expansion rates and temperature activations.
There is written info out there, I thing it was lorient.
Agree with Kurnal his final para, need to watch out the contractor uses the proper glue and not some cheap crap

davo

[Fishy]

jasper

Although I am retired, I do remember there are 3 types of IS, each with differing expansion rates and temperature activations.
There is written info out there, I thing it was lorient.
Agree with Kurnal his final para, need to watch out the contractor uses the proper glue and not some cheap crap

davo

Yup:

- Ammonium Phosphate
- Hydrated Sodium Silicate
- Intercalated Graphite

Your typical door edge seals (the ones in the PVC casings) are usually either of the last two (though only Sodium Silicate actually needs to be protected by PVC); gaskets for ironmongery are usually AP.  They have significantly different characteristics when they activate - for those that are interested.... http://www.means-of-escape.com/sites/default/files/Information%20Sheet%201.pdf.