Residential Design series F is for Flooring

June 26, 2018

Residential Design Series F is for Flooring. (With respect to Sue Grafton)

A few years back I offered to help a desperate theatre director replace his tongue and grooved floor. I was sidetracked by a note in his visitors’ book from a dancer in residence who loved the space but bemoaned the missile like splinters that she inevitably removed from her feet after a hard practise.

Replacing the floor of the theatre presented me with the same structural problems that an owner builder who decides to replace their old T@G floor is likely to encounter.

If for instance there is a substantial gap between your skirting boards and the top of the flooring then it probably indicates that the piers and footings supporting the structural timbers that are supporting the floor have sunk into the foundation material. The foundation is the soil mass under your property. The footing is the structural support on which the pier is built. Many people confuse the two.

 Most early 20th century cottages have inadequate footings. Often the footings consist of a couple of courses of bricks dug into the foundation. On these sit the piers that support the floor. If your property is in a highly reactive soil area, (i.e. large quantities of clay) or it sits in a bit of an incline where a natural water course may have flowed then at different times the foundations will be waterlogged and the footings sink into the mud.

Many properties suffer from this problem. Thankfully it is reasonably straightforward to fix. The first step is to remove the old T&G flooring. Either get into it with a pinch bar and create firewood or you can prise and cut the nails with a mechanical blade which may enable you to save some of the boards. If you plan to reuse the flooring then you must not damage the Tongue or the Groove. You really need to get yourself a reciprocating saw and cut the nails from underneath.

Once the boards have been removed you can examine the state of the bearers and joists.  Joists should be at .450centres and bearers at 1.800 centre to centre. My position in 2018 is to replace the bearers and Joists with termite proof LVL’s. (Laminated Veneer Lumber.)

The piers supporting the bearers should also be at 1.800 centre to centre.

In some cases it may be easier just to replace all of the footings and piers.  In the theatre due to money considerations we weren’t able to replace any of the structural timbers.

Where we were able too, we dug and poured new footings alongside the existing and rebuilt new piers.  Where we had two bearers meeting on the same pier we built a new pier on either side. To get our levels we water-levelled marks along the walls on either side and ran string lines across the top of the piers. Now days you would use a laser level. We measured down from the lines to get an approximate height for the piers. Naturally if you have access to a theodolite the procedure is quicker and more accurate. The footing depths and diameter should be determined by a structural engineer. Once you have removed the flooring it would be wise to get a structural inspection before you proceed. Hopefully you won’t require any underpinning of the walls but the most opportune time to do it is while the flooring is up. Once the piers have been built don’t forget to place damp-proof course on top of each pier and add an ant-cap. You may have to pack between the bearer and the pier to create an even finished floor level. Usually this is done with sections of ripped hardwood or fibro. Once again you level with a laser level.

In the case of a cottage with good skirtings you want your flooring to finish hard under the skirtings. Ideally you will be able to do this without removing the skirting boards although in some cases where the plaster is damaged  or the piers have sunk it may be unavoidable and removing the skirtings is the smart option.

The flooring in the theatre is now about eight years matured. I would imagine hundreds of people have seen scores of performances since we completed the work. The director still sends me tickets to every opening night.

Good Building and design!

Note: The views expressed in this article are of a broadly based nature and are in no way to be taken as the basis of an individual design. Should a reader wish to pursue the ideas expressed then at all times we recommend they consult with the appropriate professionals. 

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