Log Burner advice

[richo106]

Hi All

 

We are planning to have a log burner in the kitchen/diner area.

 

we are focussing on air tightness with MVHR so having a room sealed log burner. Does it need to be below 5kW? 
 

What is the minimum distance from log burner to inside of chimney? I have googled it and found 150mm so I have left 200mm to the block work to allow boarding and different size fire etc

 

what is the best way to board /plaster inside the chimney

 

I have attached a rough drawing and picture of what we are wanting to achieve. The log burners we have looked at are around 500mm wide

 

Any advice/information very much appreciated 

[ProDave]

Every manufacturer of a stove will publish the clearance distances from sides and back to "combustibles" and it will vary from manufacturer to manufacturer.

 

For instance our Medip Stoves Churchill 5 convection model requires only 150mm from side to combustible materials and 100mm from the back to combustible materials. It is 550mm wide so in an opening 900mm wide the sides could be combustible material, i.e. plasterboard.

 

The 5kW thing is irrelevant for you.  A stive under 5kW may be able to get away with no combustion air provision and just draw air from the room.  You are proposing a room sealed stove with combustion air direct from outside so you can fit any size stove that is appropriate. 

 

This is the current version of our stove, changed slightly from the one we bought several years ago https://www.mendipstoves.co.uk/churchill-5-convection-logstore-dual-control-ecodesign-woodburning-stove

[PeterW]

The issue is not just the stove but the flue - use enamel stove pipe and you need much more space to combustible materials.

 

You can get away with lining the alcove with cement board and then skimming with a high temp plaster which means you’ve sorted the non-combustible issue however you really need the stove specified to know what your limits are.

[Marvin]

1 minute ago, PeterW said:

The issue is not just the stove

but the floor as well

 

[Temp]

9 hours ago, richo106 said:

 

 

I don't believe the above meets Building Regulations.

 

Assuming the stove is certified not to raise the Hearth above 100C then the stove should be on a sheet of glass/slate/granite or similar about 12mm thick to meet Diagram 27(a) in Approved Documents J..

 

See page 38 and 39.

 

https://www.gov.uk/government/publications/combustion-appliances-and-fuel-storage-systems-approved-document-j

 

The idea is to prevent rugs creeping too close to the fire by providing a small step

 

The other dimensions for this are in Duagram 26.

Edited November 27, 2022 by Temp

[ProDave]

10 minutes ago, Temp said:

 

I don't believe the above meets Building Regulations.

 

Assuming the stove is certified not to raise the Hearth above 100C then the stove should be on a sheet of glass/slate/granite or similar about 12mm thick to meet Diagram 27(a) in Approved Documents J..

 

See page 38 and 39.

 

https://www.gov.uk/government/publications/combustion-appliances-and-fuel-storage-systems-approved-document-j

 

The idea is to prevent rugs creeping too close to the fire by providing a small step

 

The other dimensions for this are in Duagram 26.

A self builder near me had this discussion with BC and won.  It boiled down to the distance to combustibles thing.  A stove where they guarantee no more than 100 degrees at the base still needs 12mm to combustibles Presumably to cater for hot ash falling out when refueling?.  It does not need a constructional hearth.

 

The self builder argued it was 10mm tiles then 6mm tile adhesive then a floor screed so the combustible issue did not arise.  BC failed to find any reason such as a step so passed it.

 

In out last house we had a constructional hearth and tiled finish and wooden floor in the rest of the room and I deliberately set the tiles level with the wooden floor.  Again BC muttered about wanting a step but when asked to show me where is says that, he could not and passed it.

 

The 12mm thing allows you to put a 12mm sheet of glass onto a wooden floor and that will comply.  In this house we have a 20mm thick slab of granite on top of wooden flooring.

[Temp]

10 minutes ago, ProDave said:

The 12mm thing allows you to put a 12mm sheet of glass onto a wooden floor and that will comply.  In this house we have a 20mm thick slab of granite on top of wooden flooring.

 

Same here.

[Roundtuit]

Straight on to tiles here, as per thr photo.  BC never queried it.

[ETC]

1 hour ago, Roundtuit said:

Straight on to tiles here, as per thr photo.  BC never queried it.

Doesn’t comply. A change in level is required.

[ProDave]

So where is the diagram showing the case where the whole room is non combustible flooring.  It only shows there must be a transition from combustible to non combustible but does not show what, if anything, is needed where the whole room is non combustible.

[Roundtuit]

1 hour ago, ETC said:

Doesn’t comply. A change in level is required.

Hmm... installed by HETAS installer, and signed off by BC.  I think it's OK.

[MJNewton]

11 hours ago, ProDave said:

So where is the diagram showing the case where the whole room is non combustible flooring.  It only shows there must be a transition from combustible to non combustible but does not show what, if anything, is needed where the whole room is non combustible.

 

That falls to Diagram 26:

 

 

And the corresponding text in particular:

 

2.26 An appliance should be located on a hearth so that it is surrounded by a surface free of combustible material as shown in Diagram 26. This surface may be part of the surface of the hearth provided in accordance with Paragraph 2.23, or it may be the surface of a superimposed hearth laid wholly or partly upon a constructional hearth. The boundary of this surface should be visually apparent to provide a warning to the building occupants and to discourage combustible floor finishes such as carpet from being laid too close to the appliance. A way of achieving this would be to provide a change in level.

 

[ETC]

11 hours ago, ProDave said:

So where is the diagram showing the case where the whole room is non combustible flooring.  It only shows there must be a transition from combustible to non combustible but does not show what, if anything, is needed where the whole room is non combustible.

The reason for the change in level is so that a combustible material is unlikely to come in contact with the appliance. Doesn’t matter if the complete floor is non-combustible.

[ETC]

10 hours ago, Roundtuit said:

Hmm... installed by HETAS installer, and signed off by BC.  I think it's OK.

Still doesn’t comply. BCO slipped up. I wouldn’t pass it.

[MJNewton]

12 hours ago, ETC said:

Doesn’t comply. A change in level is required.

 

Comply with what exactly? You shouldn't conflate Approved Documents with the Building Regulations. The ADs merely offer practical guidance on how the BRs can be met which, generally (but not always) speaking, means that if you follow the ADs then there is a presumption of compliance with the BRs. Following the ADs makes the BCO's job relatively straightforward, however they are always in the position of allowing consideration of alternative approaches which, if they are content still meet the provisions of the BRs (which are very high-level and not detailed like the ADs are), can be accepted and signed off as such. There is nothing in the BRs that explicitly requires a change in level.

[ETC]

Just now, MJNewton said:

 

Comply with what exactly? You shouldn't conflate Approved Documents with the Building Regulations. The ADs merely offer practical guidance on how the BRs can be met which, generally (but not always) speaking, means that if you follow the ADs then there is a presumption of compliance with the BRs. Following the ADs makes the BCO's job relatively straightforward, however they are always in the position of allowing consideration of alternative approaches which, if they are content still meet the provisions of the BRs (which are very high-level and not detailed like the ADs are), can be accepted and signed off as such. There is nothing in the BRs that explicitly requires a change in level.

I know the difference between the Regulations and the Guidance - I enforce them.

 

If the Guidance cannot be complied with the onus is on the applicant to show how he or she has complied with the Regulations in some another way.

[saveasteading]

6 minutes ago, MJNewton said:

There is nothing in the BRs that explicitly requires a change in level.

If in doubt go back to the short bit in green. You may then have to explain the logic and low risk of your proposal.

[MJNewton]

12 minutes ago, ETC said:

If the Guidance cannot be complied with the onus is on the applicant to show how he or she has complied with the Regulations in some another way.

 

Yes, and on that I think we're in complete agreement.

 

Here are the BRs on the subject:

 

Quote

Protection of building

 

J4. Combustion appliances and fluepipes shall be so installed, and fireplaces and chimneys shall be so constructed and installed, as to reduce to a reasonable level the risk of people suffering burns or the building catching fire in consequence of their use.

 

I can perfectly understand a BCO being content with a non-combustible finished flooring surface and construction not requiring a raised hearth.

Edited November 28, 2022 by MJNewton

[ProDave]

Quote

The boundary of this surface should be visually apparent to provide a warning to the building occupants and to discourage combustible floor finishes such as carpet from being laid too close to the appliance. A way of achieving this would be to provide a change in level.

so it says a way of achieving this is a change of level.  Note that is not the only way, it needs to be "visually apparent" so a change from tile to wood is pretty visually apparent, without a change of level.

 

If they really required a change of level it would say there must be a change of level, not that a change of level is one way to make it visually apparent. 

 

This is very much open to interpretation, a very poorly written definition.

[ETC]

36 minutes ago, MJNewton said:

 

Yes, and on that I think we're in complete agreement.

 

Here are the BRs on the subject:

 

 

I can perfectly understand a BCO being content with a non-combustible finished flooring surface and construction not requiring a raised hearth.

As a BCO I wouldn’t be happy to accept a stove without a hearth with a change in level. It is unsafe. Where the complete floor is tiled there is nothing to stop a rug being placed close to the stove. That would satisfy J4.

 

J4. Combustion appliances and fluepipes shall be so installed, and fireplaces and chimneys shall be so constructed and installed, as to reduce to a reasonable level the risk of people suffering burns or the building catching fire in consequence of their use.

Edited November 28, 2022 by ETC

[MJNewton]

11 minutes ago, ETC said:

As a BCO I wouldn’t be happy to accept a stove without a hearth with a change in level. It is unsafe. Where the complete floor is tiled there is nothing to stop a rug being placed close to the stove.

 

Entirely your prerogative, and a reasonable position to take. Other BCOs may take a different view and be perfectly content with it, and they'd be no less right or wrong than you in doing so.

 

The BRs simply aren't specific enough to be able to draw a specific line on this, and their aim is only reducing risk to a 'reasonable level' - not completely eliminating it otherwise we'd also be discussing the need to put in measures to stop people putting wood-filled wicker baskets on their hearth (raised or not! )...

Edited November 28, 2022 by MJNewton

[ProDave]

13 minutes ago, ETC said:

As a BCO I wouldn’t be happy to accept a stove without a hearth with a change in level. It is unsafe. Where the complete floor is tiled there is nothing to stop a rug being placed close to the stove. That would satisfy J4.

 

J4. Combustion appliances and fluepipes shall be so installed, and fireplaces and chimneys shall be so constructed and installed, as to reduce to a reasonable level the risk of people suffering burns or the building catching fire in consequence of their use.

If you were my BCO I would contest that and ask for another opinion, as nowhere in the regs does it say a change of level is required.

[ETC]

50 minutes ago, ProDave said:

If you were my BCO I would contest that and ask for another opinion, as nowhere in the regs does it say a change of level is required.

😂 Sorry Dave - you wouldn’t get too far asking another BCO - we all sing off the same hymn sheet in our office. But good luck!

 

Seriously though - We would always ask for a raised hearth-it’s clear from the Regulations that the requirement is to have an installation that is safe and the Guidance does refer to a change in level.

 

Thank you.

 

Here endeth the lesson!

[ProDave]

But the regs do NOT call for a change of level.  They call for "visually apparent boundary" so would you accept a totally level tiled floor, but with the hearth bit tiled in different coloured tiles to give that visual boundary?

[saveasteading]

Provide the bco with a written explanation of your proposal and how it complies with the basics of the regulation and, if it makes sense, they are likely to accept it.

It goes in their file as cover too.

Given how far a glowing ember can tumble I think it is a serious concern...and we must not assume that a future user will have the sense that is required.

I would like an ember catching edgeto the hearth  if there was a carpet.