Bungalow Barn

[Snowbeetle]

Hello fellow self-builders, 


We are at the start of our first self-build project. In South Lakes and massively grateful to find ourselves (very unexpected) with this opportunity to create a great place to bring up the kids.

So far:

We have cleared the site and begun demolition of the unwanted structures such as the animal stalls and partition wall. 

Installed a waste water treatment unit (currently servicing our on-site temp accommodation) and laid pipes for future connection to house toilets and drains. 

 

We are currently wrestling with whether to put in a limecrete floor or ordinary cement floor. Money is a factor. Our risk concern with ordinary cement is the possible rising damp problems it could give us in a lime pointed solid stone wall - but it's cheaper and maybe won't cause those problems. Concerns with the lime floor are the uncertainty of the level of skill required to self-lay it, but it is compatible with a breathable building envelope so preferable if we can afford it and not botch it. 

Once that decision has been wrangled (any thoughts much appreciated). We will aim to get that installed this summer.  

 

I see I am not the only person starting a thread here in barn conversions - nice to have the company Robjones <waves>

 

ttfn

 

 

[Lesgrandepotato]

Waves from the sticky toffee pudding village. 

[Simplysimon]

lime breathes, cement/concrete doesn't, however, i'm sure you will be putting a dpm in whichever route you go down or am i picking up the wrong end of the stick?

[DavidFrancis]

There may not be that much difference in the breathability of lime-based mortar and cement-based.  See this discussion (admitedly on render)

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10263

 

If you search for " Breathability: The Key to Building Performance" you will find the paper referred to.  It is written by Neil May who is, inter alia, one of the "experts" at the Sustainable Traditional Buildings Alliance.  (Never met the man myself.)

[Simplysimon]

@DavidFrancis reading through the posts the article seems to have dubious referencing and numbers not tallying, didn't read the article tbh. looking at it from a practical side, one of the worst things you can do is cement render a sandstone wall whereas a lime render is fine.

[Snowbeetle]

1 hour ago, Simplysimon said:

lime breathes, cement/concrete doesn't, however, i'm sure you will be putting a dpm in whichever route you go down or am i picking up the wrong end of the stick?

Hi Simplysimon, if we used lime we would not use a DPM, having an impermeable water barrier rather negates the point of a breathable floor as I understand it (based on reading around, SPAB etc). So instead a glass foam base layer which acts as a capillary break and insulation followed by the lime slab. Would use a DPM with concrete though to help reduce salts uptake which encourages damp. This is based on guidance not direct personal experience. I think you can get away with a concrete floor and lime pointed walls if the prevailing ground and atmosphere conditions mean that the water under the slab seeking to escape is minimal or low enough not to cause a problem. However, we live in Cumbria, where it is wet a lot! So the atmosphere may not lend itself to external evaporation enough. Ultimately only hindsight will tell us for sure whether we've gone down the right road I think, but it seems right to me that waterproof meeting water resistant is a point where problems could well occur.

[Snowbeetle]

1 hour ago, DavidFrancis said:

There may not be that much difference in the breathability of lime-based mortar and cement-based.  See this discussion (admitedly on render)

http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=10263

 

If you search for " Breathability: The Key to Building Performance" you will find the paper referred to.  It is written by Neil May who is, inter alia, one of the "experts" at the Sustainable Traditional Buildings Alliance.  (Never met the man myself.)

Thanks for the link- some reading for me there. I had a chat with some lime people today (obviously not impartial) but I am leaning towards limecrete floor currently. 

[Luckylad]

Hello 

you’ll have some spectacular views from your barn!

Just out of curiosity,have you done a price comparison between a concrete floor and a limecrete floor?

 

[Snowbeetle]

33 minutes ago, Luckylad said:

Hello 

you’ll have some spectacular views from your barn!

Just out of curiosity,have you done a price comparison between a concrete floor and a limecrete floor?

 

Thanks, I did cheat a bit those views are actually a tiny walk up the hill behind the barn - but hey that's splitting hairs, the view from the windows could be worse for sure - maybe not so panoramic but scenic certainly, and a HUGE difference from our previous home.  

Funnily enough, you should ask, we did originally do an internet search based cost comparison during the process of costing the project for the mortgage, and concrete came out about 40% cheaper. However, I have got some hard figures today which indicate the difference is far less than that much more on a par. Possibly because the insulation layer material we looked at was different. Which is why I am now leaning much more towards the limecrete, since I'd rather give the breathable materials a proper chance to do their work than half and half it and then not know what to blame if it fails. At the end of the day a building is a dynamic system and while physics tells us how water, heat and air react together, the exact way that plays out in a building depends on so many factors interacting, no-one can say exactly what will happen in your house. So I will just take a belt and braces approach and try to use best technique on everything. . 

[Simplysimon]

@Snowbeetle does the foamed glass come in at a reasonable price

[PeterW]

Welcome 

 

What is your target insulation value for the floor ..? Whilst Limecrete and Foamglas may be more on a par for a very low performing floor, you may struggle to get close to building regs levels. 

 

How are you planning on insulating the walls ..? You may be better trying to create a vapour impermeable bubble inside the building and use MVHR to control building moisture and let the walls do their own thing. 

[Snowbeetle]

13 hours ago, Simplysimon said:

@Snowbeetle does the foamed glass come in at a reasonable price

It does, very fair partly because it is very light despite good compression strength so transport costs are lower compared to heavy materials and also it is made from recycled glass so the raw materials are not too high. 

[Snowbeetle]

13 hours ago, PeterW said:

Welcome 

 

What is your target insulation value for the floor ..? Whilst Limecrete and Foamglas may be more on a par for a very low performing floor, you may struggle to get close to building regs levels. 

 

How are you planning on insulating the walls ..? You may be better trying to create a vapour impermeable bubble inside the building and use MVHR to control building moisture and let the walls do their own thing. 

Hi PeterW, 

because it is conversion not new build the regs on U-value I have to meet are not so high (as you no doubt know). I am expecting to get at least 0.29 on the floor (with 150mm insulation) but hopefully better if I can dig deep enough to get a deeper layer of insulation in. Not sure what U-value an exisiting low performing floor would be... I'm a bit new to this.