Heating: First Floor - Pipes and screed

When we first started planning the house, the idea of installing underfloor heating upstairs seemed impossible to achieve. Most builders we spoke to 'advised' that we either use electric heaters, conventional radiators or simply avoid putting any heating upstairs at all! Since our heating would be powered using a heat pump, radiators would be a very inefficient option - unlike radiators, heat pumps are designed to work at relatively low temperatures, so using it with radiators would push running costs through the roof.

After much research and speaking to several specialist underfloor heating installers, we decided the best option for us was a dry screed floor-on-floor system - and this is what we did...

We started out with a clean, dry plywood floor which had been installed as part of the timber frame construction.





Next we screwed down lengths of batten. We had to plan the batten layout around how the underfloor heating pipes were going to sit.







As well as screwing down the battens, we used a strong wood glue to help minimise any future creaks or squeaks when walking on the wooden floor that would eventually go on top of this layer.





We tried to screw the battens directly into the floor joists below wherever possible for extra rigidity.





One unexpected problem we encountered was that the electricians had run cables right under the plywood floor, so we had to keep checking and measuring from the ground floor below to avoid screwing into any wiring.

The site inspector kept a close watch on our progress.

Batten-fest! 78 square metres of floor space had to be covered.

We had to constantly keep in mind how the heating pipes would fit around the battens and leave gaps and pathways where needed.





We had an underfloor heating plan pinned up for reference along with our own batten plan.

Once all the battens had been fixed in place, we installed the underfloor heating manifold. Having watched the plumber install the downstairs manifold, Alan felt confident enough to do this himself.

Each circuit of underfloor heating pipe has to be laid in one unbroken run. The large coil of pipe goes from the manifold, runs around its designated room before returning back to the manifold.





Alan fitting the underfloor heating pipes to the manifold.

In order to maximise the heat pump efficiency, the plan called for the pipes to be laid quite close together. This meant that we had to take extra care when bending the pipe loops to avoid kinking them.





This is one full circuit completed in bedroom 3. The second half of the room will have another circuit installed. It is more efficient to use two shorter circuits, rather than one long run, to minimise heat losses.





As each circuit is completed, the road to the manifold becomes ever more congested.





The main bedroom uses three circuits. The one pictured below heats both the walk-in wardrobe and the en-suite bathroom...





... whilst the other two circuits cover the rest of the main bedroom.









To ensure that the pipes were equally spaced out (avoiding any cold spots) we cut blocks of wood to appropriate sizes and used them as spacers. Much easier and quicker than constantly measuring every loop.





We had several late nights working to get it all finished. The landing was particularly tricky as it was the main thoroughfare for all the pipes going to and from the manifold.





The manifold with all the pipes completed. A tight squeeze.





Planning the pipe runs for the bathrooms was more involved as we needed to take into account where all the bathroom furniture was going to be positioned. We had marked out the showers and the toilets but we were still unsure exactly where the bath would sit. The best solution was to buy the bath, haul it upstairs and decide from there.

The bath ready to be hoisted up using a pulley.





We tried placing the bath in different positions before finally agreeing where it should go. Since Alan and I differed in our opinion, this took some considerable time!

After the historic compromise had been reached, we finished the pipe circuit for the bathroom.

With all the circuits complete, Alan filled the system with water, flushed any air out of it and pressure tested it. Once we were happy that there were no leaks, we started work on the dry screed.





As we were new to this, we used the walk-in wardrobe as a test bed.




Once we were happy with the result we got going on the rest of the rooms.





We had plenty of sand and cement left over from the outside render. Alan hauled up heavy buckets of sand using the pulley...





... and then we mixed each batch with cement by hand (or rather by shovel). This was physically hard work as we were laying 78 square metres of screed. I wish we'd hired a cement mixer as this would have saved us a lot of time and backache!

While Alan went to lug more sand, I spread and levelled the screed over the pipes between the battens.





The site inspector would often drop by to check on our progress...

Luckily he seemed satisfied with my work.





Halfway there...





Working late again...

Using a dry screed is very effective compared to other underfloor systems such as metal spreader plates. It is a lot cheaper in materials, has greater thermal mass (so it will conduct and hold the heat from the pipes more efficiently) and is relatively straightforward to install.

The one big drawback of this system is the weight - dumping several tons of sand and cement onto a standard floor construction would not be a good idea! Critically, we had decided to use a dry screed system upstairs at a very early planning stage before we had finalised the design of the timber frame. This allowed the timber frame company to calculate the structural effects of the extra floor loading and they beefed up all the floor joists accordingly.





Hooray! The underfloor heating upstairs is completed. Though it was hard work, by doing it ourselves we had saved a few thousand pounds.





On a sad note, poor Custard passed away during this time. She used to love sleeping on the big pile of sand outside the front door. Here she is enjoying a rest on her beloved sand mattress.

Groundwork: Septic tank

Installing new septic tanks or fancy sewage treatment plants can be quite an expensive business. As we are building on a rather tight budget, we decided that we would use the existing septic tank for the new house. Built for the old bungalow next door, the septic tank is located in the farmer's field nearby (see pic below) - it's pretty large and luckily was still in reasonable condition when we bought the plot so the local authority seemed happy enough for us to use it for the new house.





However, back in 2013 just before starting the new house build, a farm worker somehow managed to drive a heavy tractor straight over our septic tank, wrecking the concrete lid, the covers and causing massive structural damage to the whole thing. Great...







Fortunately after some discussion, the farmer who owned the field agreed to take responsibility for the repairs, so we patched up the tank temporarily with some sheet materials to make it safe for any passing people or animals. You really would not want to plunge into that pit of hell!







As the months went by, it became clear that the farmer was struggling to find someone qualified to fix the damage and even more worryingly, now seemed keen on getting his own workers in to effect some kind of repair/bodge.

At the same time, we'd just started digging the foundations of our new house and had just been presented with a whopping bill for the disposal of all the excavated soil. The solution was staring us in the face - we could save thousands if the farmer would agree to take all our excavated soil and in turn he wouldn't have to worry about how to fix the septic tank. As long as we could get it repaired ourselves for less than the cost of the soil disposal, everyone would be happy...

The farmer agreed to the deal so we got the groundworkers to dump all the soil in the field. It made a huge earth bank that stretched several hundred meters.





Working in winter, the dumper truck also churned up the field, turning it into a bit of a swamp. Oops.

A few months later, the farmer had used all our soil to make up new earth banks... 

... and over time, nature took care of the rest.





With the build taking up so much of our time, we sidestepped the issue of the broken septic tank for as long as we could but as winter approached, its deteriorating condition meant we had to address it sooner rather than later. Cutting back all the overgrown plants revealed how bad the damage was.









After much to-ing and fro-ing, getting several ludicrously high quotes and a few false starts, we finally employed a local specialist firm to help with the repair. The first step was to remove all the old broken material to get a proper look inside (yuk). It's lucky that Alan volunteered to help Dean with all the work as under the old broken concrete lid, there were two huge slabs of slate which he carefully removed - these look like they could be ideal for outside the front and side doors of the new house (after a good clean of course!)  





Once the lid was off, the damage to the top of the tank walls could be properly examined. It didn't look too bad, but we wouldn't know for sure until the tank was emptied.





The tanker arrived...

... dropped a pipe into the field...





... and started pumping out both of the tank's chambers.





Despite its contents, a properly-functioning septic tank is not as stinky as you might think. The 'poop' in the primary chamber forms a crust on top and is broken down by bacteria and micro-organisms. The resulting liquid flows into the second chamber from where it is gradually leached out into the field via a large network of perforated underground pipes.







Luckily the main part of the tank appeared to be undamaged and looked to be in reasonable condition.





Once the tank was emptied, all the rubble and debris from the broken lid needed to be removed from the bottom. Alan wisely chose not to volunteer for this part of the job.





Dean getting down to 'business'... he requested that we didn't flush the toilet while he was in such a perilous position.





After cleaning out the tank, Dean replaced some of the broken pipework.





We used the last few blocks left over from the house build to fix the central wall.

The tank was beginning to look a bit healthier. All it needed now was a new lid.

Dean brought some precast concrete covers which he and Alan hauled manually into place.





Once the three concrete panels were set level, the metal inspection covers could go on.







To finish off, the concrete panels and covers were cemented into place.









We rarely get any tractors in that field but to avoid any possibility of it being driven over again, we erected a small rope fence around the septic tank to let farm workers know it was there.