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Treading carefully with sub-floor restorations

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20170402_171838When embarking on any restoration project it’s vital to do your research first. New builds offer the comforts of already built sub-floors, complete with their state-of-the-art insulation flooring systems which comply with the most stringent of building regulations.

However, that doesn’t leave much to the imagination, and therefore we decided on a Victorian restoration of a 1905 quarry tile floor.

As an end terrace, the property was the first one the builder built on the street, and whilst retaining original features is always high up on the list of priorities, unfortunately the building lies at the bottom of a sloping street of terraced houses and over time the building had succumbed to subsidence.

This left the quarry tiles impacted on each other, some with large grout gaps, some flush tight, and others buckled and raised, bumpy and unsightly. Sadly the original stones had also been heavily scratched, and then painted black and white, whilst the authenticity of the floor had been lost.

It’s very difficult to judge what lies beneath such quarry tiles floors. Ash beds can often open up a whole heap of issues and be incredibly dusty to work with. Similarly, the ground clay can be wet and make the environment dirty to work with.

The only thing for it….take a risk, and excavate the floor.

To begin the project we found one of the most uneven quarry tiles with a deep grout gap. Using a chisel and mallet we knocked down underneath and levered the tile upwards. Surprisingly it popped straight out in one piece. Could this be a good sign?

A second piece a few tiles away was then removed, and then a third until several tiles revealed a diamond shaped opening in the floor.

Beneath the tiles was a bed of bone dry ash. A small potting spade was used to remove some of the ash and we soon filled up a large black rubble sack. Approximately 300mm below the tile level was a clay bed. Old quarry tile floors could breathe. They allowed the air to circulate but this sometimes led to mould and damp.

After a day of chipping away at the 4 metre long hallway, many of the tiles had been lifted out from the ground and were outside in rubble sack ready for the reclamation yard.

Fortunately it had been a dry spell which meant the ground soil was completely free of moisture and work could continue at any time of day or night.

However, it would be worth ensuring you’re ready for several key eventualities if considering taking on such a restoration project.

First of all, the volume of rubble. It seemingly never ends. We loaded up six rubble sacks and it seemed as though we’d taken nothing at all away from the ash bed. Several hours and days later, 100 rubble sacks and dozens of visits to the local household recycling plant we had removed all of the ash and a significant volume of clay to a complete depth of 450mm.

We visited Selco Builders Warehouse and got a 1200 gauge damp proof membrane, some Jablite Jabfloor Classic some type 1 MOT hardcore and some sharp sand.

While the clay had been down for over 100 years and was rock hard, the tiles had become uneven and so looking at the bumps in the original substrate, it was important to wacker the MOT to achieve a solid foundation. The craftsmanship of the foundation bricks was impeccable. The rich terracotta bricks hadn’t shifted an inch in all those years and provided a sturdy rectangular basin to work from within the hall.

However, what was challenging was that wackerplates are not seen as environmentally safe for use inside buildings as 95% of the marketshare are petrol based. The fumes being as toxic as they are have led to more than one fatality over the years and we were committed to offering readers the opportunity to find out about other methods.

brDan Edwards, a highly trained product guru from Wacker Neuson visited the site to demonstrate the Emission-free, battery-powered rammer AS 50. Both the environment and the operator are protected during compaction work with the battery-powered rammer AS 50. Due to the entirely emission-free working principle, work can easily be carried out in poorly ventilated trench applications or in sensitive vicinities. Thanks to a parallel guidance specifically developed for the rammer, the entire handle area of the battery-powered rammer AS 50 is vibration-decoupled with low hand-arm vibrations (HAV) for the operator. It was a pleasure to use and it made quick work of the floor levelling required for the 4m by 1m space.

Once the wacker had done its job we blind sanded the Type 1 and laid the first sheet of DPM around the perimeter of the floor.

The insulation was then laid at a depth of 100mm ready for our extremely helpful friends at Exact Mix Concrete who delivered a strong cubic metre of c30 mix concrete.

It is important to acknowledge the complexity of an indoor concrete pour. Knowing the exact measurements you may need, hiring a builder to coincide with the precise timings of your project are both difficult challenges to master.

However, Exact Mix had the professionalism and skill to lay the initial bed of concrete exactly level prior to our Weber Floor Levelling being completed by our master tiler.

We waited several weeks for the concrete to dry out. It’s approximately 1 day per mm to ensure you’re completely safe and avoid any issues with the floor in the future, although there are concrete companies that can add chemicals and treatments which speed this process up significantly.

weber-floor-flexmed1Garry Morris from Weber is an expert in his field and understands flooring more than most. He recommended a particular product, weberfloor flex levelling compound. This rapid setting, fibre reinforced levelling compound is suitable for most substrates including heated screeds and wood. It was excellent for this project due to the fact that it needed to fill and level a 27mm void between the concrete level and the tile adhesive.

The product had excellent Low Dust Technology reducing waste and mess whilst making it more comfortable to use.  The rapid-setting properties meant that it was ready for light foot-traffic after 1-2 hours, however, we didn’t return until the next day.

Before applying the levelling compound we applied weber PR360, an excellent priming solution. This is suitable for the preparation of most substrates prior to the application of tile adhesives and levelling compounds. It offers good alkali resistance and adhesion properties in both wet and dry environments.

The levelling compound went down quickly, simply needing to be mixed with water and then carefully poured in to the prepared sub-base. It created a stunning level space, ready for tiling, sealing any cracks and spots that may have previously given cause for concern.

The finished result was a sub-floor prepared for the next stage of the restoration project, the Victorian tiling which you can read about next time.  For this element of the project we’ll be using weberset pro lite rapid, which is an ultra flexible, lightweight and rapid setting tile adhesive after first priming with weber PR360 multi-purpose priming solution which improves porosity and adhesion.  Finally we’ll use weber joint pro, a flexible, water repellent wall and floor grout in grey.

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