Home  5  Books  5  GBEzine  5  News  5  HelpDesk  5  Register  5  GreenBuilding.co.uk
Not signed in (Sign In)

Categories



Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

PLEASE NOTE: A download link for Volume 1 will be sent to you by email and Volume 2 will be sent to you by post as a book.

Buy individually or both books together. Delivery is free!


powered by Surfing Waves




Vanilla 1.0.3 is a product of Lussumo. More Information: Documentation, Community Support.

Welcome to new Forum Visitors
Join the forum now and benefit from discussions with thousands of other green building fans and discounts on Green Building Press publications: Apply now.




    • CommentAuthorLehobbit
    • CommentTimeOct 11th 2021 edited
     
    Hello all we are installing a Burley Wakerley 12 to 18 kw wood burner in a our renovation project in the Massif Central in France. We had a Burlely Brampton 8 to 12 Kw in our previous French renovation and it was beyond amazing - crazy heat and efficiency!

    The Burely will be installed in the existing fireplace (which we will refurbish) and will be room sealed with a tube on the rear of the stove going through the 600mm thick granite wall to the outside to draw in combustion air.

    The stone walls are going to be internally rendered with a 60 to 80mm thick layer of hemp lime and then lime plaster. We may even in addition render externally with a layer of hemp lime. It depends on what the external stone work looks like once I have removed the cement render from the west facing gable end (a huge task).

    I have attached a photo to show the current fireplace. I have removed some old (circa 1960's) concrete from around the large and extremely heavy granite slab which the current range its on. Underneath is a gravelly soil. I want to create a higher and level hearth for the Burley to sit on, probably coming up about 10cm from the current level. I don't plan to remove the existing hearth granite slab as it looks seriously heavy.

    I wish to also extend the hearth outwards from the fireplace so the Burley can sit more into the room. Also we will be having a pine insulated wooden floor over the exisiting concrete block and beam floor so the extended tled hearth will protect the wooden floor from the Burley's serious heat output.

    I have a few questions and I am looking for suggestions.

    1.) What would be the best way to create a raised (10cm thick) insulated slab? My ideas was to tile over the slab with some nice rustic tiles for the Burley to sit on. I was thinking of putting 40mm of PIR/foam insulation and then 60mm of level concrete mix over the top to tile onto, creating the slab using wooden shuttering.

    Do I need to put a DPC under the concrete slab/insulation and around the edges where it meets the rear stone wall and fireplace sides?

    2.) Anyone have a better suggestion on how to do it? Maybe a limecrete slab without a DPC?

    3.) Before rendering with hemp/lime mix what would you use to remove the soot staining from the stones on the rear of the fireplace? I know I will be applying hemp lime to the wall but I am worried about soot stains bleeding through the hemp lime. I have read there are various chemicals such as Trisodium phospate that could work...any thoughts?

    Sorry it's not the best photo!!









    :cry:
      Old fireplace three.jpg
    • CommentAuthortychwarel
    • CommentTimeOct 12th 2021
     
    I wouldn't use PIR under concrete as it may well get hot enough to melt or even catch fire. why not make up a foam concrete step using thermalite blocks laid flat or pour a Leca or vermiculite concrete mix, Yes put a dpc under the lot
    • CommentAuthorLehobbit
    • CommentTime7 days ago
     
    <blockquote><cite>Posted By: tychwarel</cite>I wouldn't use PIR under concrete as it may well get hot enough to melt or even catch fire. why not make up a foam concrete step using thermalite blocks laid flat or pour a Leca or vermiculite concrete mix, Yes put a dpc under the lot</blockquote>

    I like the idea of making an insulated slab to go under the stove. By my calculations the slab will be about 10cm deep by 1.5 metres deep and around 2 metres wide. This means I would need need 3 x 100 litre bags of vermiculite. It only costs €17.49 per bag so this is a good solution. Thanks for the suggestion.
  1.  
    Posted By: LehobbitWhat would be the best way to create a raised (10cm thick) insulated slab?

    10cm is not very thick to have both insulation and concrete without the risk of the concrete slab cracking. I would say a max of 25mm insulation to leave 75mm for the concrete and the concrete should be a strong mix with small aggregate, probably max. 15 - 20mm and I would throw in some rebar mesh for good measure. The slab will probably be under more thermal tensions than most concrete and you don't want the thing cracking after you have tiled it.

    Vermiculite is light weight and granular and when laying concrete on top of it it is very easy to displace the vermiculite with the concrete. One solution is to mix the vermiculite with cement, lay it down and then spray with water. Once set then concrete on top. An alternative would be to use dense rockwool which over here can be got dense enough to lay under concrete without deforming. And of course rockwool is both heat and fire proof.

    Re DPC under the slab the usual answer is yes but less important if the stone walls to which the slab abuts has no DPC If you do put a DPC in then carry it up the sides to stop any damp coming in from the walls. (I'm betting here that there is no DPC in the building structure).
    • CommentAuthorLehobbit
    • CommentTime6 days ago edited
     
    Hi Peter. Thanks for the advice. I can probably go with a thicker slab but plan to use vermiculite concrete instead of insulation as suggested by Tychwarel. I think 15cm thick total will be okay. I would do a 10cm layer of vermiculite mixed with cement and then a 5cm sharp sand/fine gravel/cement screed over the top to tile onto. I will shutter the sides with timber at the front. What do you think?

    There is no DPC under the granite stone walls. However at the front of the fireplace is an existing poured concrete floor this has a basic plastic sheeting DPC underneath it. There is also a small cave (cellar) under part of the floor and this is concrete block and beam.
  2.  
    Posted By: LehobbitHi Peter. Thanks for the advice. I can probably go with a thicker slab but plan to use vermiculite concrete instead of insulation as suggested by Tychwarel. I think 15cm thick total will be okay. I would do a 10cm layer of vermiculite mixed with cement and then a 5cm sharp sand/fine gravel/cement screed over the top to tile onto. I will shutter the sides with timber at the front. What do you think?

    Sounds like a plan !
    see
    https://www.vermiculite.org/wp-content/uploads/2014/10/Vermiculite-Concrete.pdf
    Which contains
    For most applications, the topping mix should consist of 65mm (2 ½ inches) of 1:4 sharp sand/cement by volume
    screed laid over the set vermiculite concrete.

    Plus other useful bits like suitable mixes for various applications
Add your comments

    Username Password
  • Format comments as
 
   
The Ecobuilding Buzz
Site Map    |   Home    |   View Cart    |   Pressroom   |   Business   |   Links   
Logout    

© Green Building Press