Hearth-ache

Posted on October 25, 2015 by nager

Hearth-ache (n.) /hɑːθ eɪk/

The pain and stresses of trying to work out where to place your stove and constructional hearth in order to comply with impenetrable building standards documents and reams of technical sheets from the stove company.

Matt the architect was effecting a very successful poker-voice on the phone. But I just know he was thinking ‘I told you so’. He might not have said it out loud but I know if I was him I would be singing raucously to myself ‘I told you so i told you so ITOLDYOUSO!’. Fortunately for me, given the misadventures on this project, every professional involved with this project has remained entirely discrete on matters of how they think things are going, and Matt is fortunately of that ilk.

This conversation was an attempt to discover a miracle substance I could use to make my constructional hearth. It had to be an insulator, have a really high compressive strength and also be non-combustible. The internet couldn’t provide me with many ideas. The stove company suggested a mixture of perlite and concrete. But I couldn’t find any figures on how insulating this would actually be.

The first decision, of course, is whether you actually need a constructional hearth in the first place. This depends on the stove, and the temperature that the area under the stove will reach. The stove manufacturer will indicate whether you need a constructional hearth and, for our inset stove, we did. More about choosing the stove here.

And the reason that I would have been chanting ‘told-you-so!’ At top volume if I were Matt? Well it was because in his original designs the concrete floor was laid on top of the insulation. This would have meant that the constructional hearth (at least 250mm non combustible material under the stove) would have had insulation underneath. And cold bridging would not be a problem.

With the insulation and concrete reversed (for the very sensible and pragmatic reason that it was recommended by the builder and it made it considerably easier to get the house built) it was a bit more of a challenge. What I needed was a material that could form part of the constructional hearth but was also an insulator.

Fortunately Matt had an idea – try Foamglas he said. I called the very helpful chap at Foamglas who talked me through the various types and what would be best for my situation.

We decided to get 100 deep Foamglas to maximize the insulation (it has roughly half the lamda value of kingspan) and then allow the screed to fill in the space so it was 80mm thick. A 50mm concrete slab on top of that would give the belt and braces for building control of at least 125mm concrete under the stove.

I bought a box of Foamglas sheets and also a box of Foamglas perinsul- to go under the masonary wall that was to go at the back of the stove. Peninsul has a really really high compressive strength so can go under even load-bearing walls.

An engineer friend was kind enough to do some calculations for me on the back of the envelope and, although he said that Foamglas sheets with a compressive strength of xx would be plenty strong enough to support a masonry wall and certainly the stove, it would be sensible to use the perinsul with a compressive strength of 3200 for under the masonry wall.

The size of the constructional hearth and the superimposed hearth was the other puzzle. The question of using the manufacturers instructions (generally German building standards for a German stove) or Scottish Building Standards. And to confuse event further, the area of the superimposed hearth is not the same as the area and position of the constructional hearth.

I could write reams of utterly boring blurb on calculating the size of the various hearths so I’ll spare you that (there a bit more in this blog). But I’ll tell you that I did read the building standards documents, and the stove technical documents, to within an inch of their lives (I even had to call the German offices of the stove manufacturer to get the answer to a couple of my questions that the stove retailer couldn’t answer) and eventually managed to get my head around them.

In the end I had a plan. It was all a bit time-dependent, as usual, as Builder#1 was about to put the underfloor heating and screed floor in. But, of course, nothing is simple when you are piecing together lots of different builders to do different bits of the build. Builder#3 was to put in the masonry wall that would be behind the stove and mortar down the Foamglas before the floor came in. I called him a few times just to be sure it was all go.

I arrived on site one Monday morning at the very moment that the insulation was going down with a membrane on top, ready for the screed coming in the next day. The first thing I noticed was that the masonry wall was in, with the Foamglas Perinsul underneath, but the Foamglas for the hearth wasn’t there and the Kingspan insulation had already been laid down. The plastic sheet was just being laid down and stapled up the walls ready for the underfloor heating and the screed to come in.

Fortunately it was just in time and they took a saw to the Kingspan and the Foamglas and put it in (phew). The screed came in over the top and then a 50mm concrete slab cut to size went directly under the stove.

That was bit was not without mishap (what isn’t) but it all went in well and now the stove is in and fits and I am glad I went through all the Hearth-ache of working it all out. If anyone else wants to put in a constructional Hearth, I’m your woman to ask…..well perhaps not.

Here’s the definitive blog on the stove

Openreach Saga part 2

Posted on July 20, 2015 by nager

I had only posted my letter to the CEO of BT Openreach on Tuesday morning (and to my blog Monday evening). But later that same morning I received a phone call from an engineer in the Galaheilds office. He had heard I needed a line installed and was passing by when in Fort William the next day and would pop in to see the site.

He didn’t have any information about the request as my apparent order number didn’t seem to be on his system. But he’d come out nonetheless. I got his email address and phone number (a massive step forward) and hope started to grow in my heart.

I was somewhat flummoxed. How on earth could my letter (not yet picked up from the post box, and my blog (tweeted to my modest Twitter following ) receive such an immediate response? I called Stephen the builder who I’d called previously to see whether he had the local number ‘Oh you’ll never get that number’ but he’d also said he knew one of the local engineers and would check with him what was going on. He hadn’t yet spoken to his contact, so he wasn’t responsible for the miraculous movement.

Ten minutes later I found out when the next door neighbour (also a self build) called me to ask about how I was getting on with openreach. Her son had seen the blog and she had called Openreach’s emergency line before 8am to ask that the line they have been waiting on for months got installed at the same time.

It had an immediate effect. Men on the ground in 24 hours. They arrived, and our very dedicated electrician was there to receive him on, what proved to be, a flying visit. He dropped some cable and was gone.

I emailed the engineer and heard nothing. When I checked my emails I had received a posting on my blog from Anon (email nope@anon.com …?!) but posted from a BT server with this website

Appearing to give the magic number I was supposed to be calling. For Scotland this number happens to be 0800 141 2650 I called it. Held on until a recorded voice clicked on it told me the number was for builders and developers only – well includes self-builders too… So I held on past a few more rings. Then the voice clicked on again.

‘The person you are calling cannot take your call right now and there is no voicemail.’

To be continued….

Anticipation is growing..

Posted on March 27, 2014 by nager

It’s soon. Yes I think we might be talking to builders about building this house almost imminently. Two and a half years since we bought the plot and we may be nearly ready to go.

It’s not as simple as we start building as soon as we accept a builders’ tender though. We have building control for the base but wanted to keep the options open as much as possible with the timber frame system. This means that we have estimated our costs on the basis of a scotframe timber frame, but are open to builders suggesting other systems that match the spec. We therefore have to wait until we know the system we will be using before we go for building control for the building.

So we have a series of steps that have to wait for the step before.
1. Quantity Surveyor report and bill of quantities (to take 3-4 weeks)
2. Send out tender to builders and wait 4-6 weeks
3. decide on builder and issue contract (some negotiations and changes at this stage as we know costs)
4. Go to building control for the building
5. However I think at the same time we should be able to start on the foundations and get the timber frame started being designed and manufactured (6 weeks)
6. Then building goes up – wind and watertight in 4 days (yes you heard that right – FOUR DAYS!)

I think it might be wise to not start planning the house warming just yet.