Order Conditions and site practise guidelines.
We supply a comprehensive floor fitting service by our experienced, skilled fitters, and can quote you according to your particular circumstances, please ask for prices and details.
If you are laying a floor yourself here are some guidelines:
Hardwood is a living material which reacts to changes in relative humidity. Wood gains and loses moisture before and after installation, as surrounding conditions fluctuate. Wood expands in the summer when humidity level is high and contracts in the winter when the humidity level is much lower. To minimise the expansion/contraction of your hardwood floor it is recommended that the room should be well ventilated and the relative humidity level not exceed 65%.
Before you begin, plastering and cement work must be completely dry. Ensure that the sub-floor is flat, level and dry before installation.
It is strongly recommended that the wood flooring be left to acclimatise at room temperature for a period of at least 5 days in the case of solid timber and 24 hours for engineered floors at the ideal relative humidity level of about 45%.
Sub-floors should be dry and level, and fall no more than + / – 3mm over 3.0m in any direction.
New concrete normally takes around 1 month per 25mm of depth to dry, or 1mm per day, but faster drying products are available so readings should be taken with a moisture meter or hygrometer prior to installation.
In the case of these faster drying subfloors, if we are installing the floor then we should be made aware in writing of their composition in case any special conditions apply or treatment is required.
All building work including wet trades should be finished; there should be no visible or measured signs of moisture or condensation.
The building should be fully glazed and heating should commissioned (including normal ventilation) to its operating temperature for at least 2 weeks prior to the floor being fitted.
Kitchen manufacturers and suppliers will often suggest laying the floor before the kitchen is installed. There is no good reason for this and we do not recommend it, especially with large and/or heavy units. In most cases it is quite simple to lay the wood upto the installed kitchen which also saves the risk of the weight preventing movement in the floor and the client paying for wood that will never be seen.
1. To Lay a Solid Floor
Moisture Test – Concrete Slabs
The single biggest cause of problems with wood floors is laying over concrete screeds before the screed is sufficiently dry. It is therefore important to make tests in several areas of the room. When a test indicates excess moisture, wait for the concrete to dry naturally or accelerate drying with heat and ventilation, then test again before installing floor.
- Rubber mat method Useful only on light coloured concrete.
Lay a flat, non corrugated rubber mat on the slab. Place a weight on top to prevent moisture from escaping and allow the mat to remain 24 hours. If the covered area shows dark, wet marks, too much moisture is present.
- Polyethylene film method
Tape a 12” (30cm) square of clear polyethylene film to the slab with plastic moisture resistant tape sealing all four edges. If no condensation collects under the film after 24 hours, the concrete is dry enough for floor installation.
- Tramex meter
Alternatively you can hire a moisture meter from the Andrew Banks, if the reading is below 4% MC (or 3% in conjunction with underfloor heating) then the concrete should be dry enough.
The humidity should be between 45 and 65% and the temperature between 18° and 25°C during installation and these conditions should remain after installation as far as possible, a dehumidifier/humidifier can be installed if you are concerned about increases/decreases in humidity in the building at any point after the floor is laid.
Floors are generally dried to 10% +/- 2% to make them as compatible and stable as possible with these “normal” living conditions. However you should still expect some seasonal movement, the wider the board the more noticeable any movement will be and it would be quite normal to expect a small gap to appear in winter when the heating is on and close up in the summer as humidity is introduced. You should also expect some cupping on wider solid boards.
Installation Method – Structural Floors
Solid floors 18mm or thicker are structural floors and should be nailed to battens/joists, chipboard or plywood. Chipboard is the simplest and most cost effective way of providing a good sub-floor but battens can be used if a void is required to provide space for pipes, cabling and other services.
Plywood or Chipboard on Concrete – Begin by covering the slab with a vapour retarder of either underlay with built in MC barrier, building paper or polyethylene. The sheet material can be floated or fixed down make sure it is laid at right angles to the direction the finished floor needs to be laid this will help prevent cracks along panel edges.
Batten system – Lay out battens (approx 25 x 50mm in size) at the specified distances and level them by packing. Packing must be fixed to the battens and/or sub-floor.
To lay the floor on Board/Timber base – For new construction or renovation.
- Maintain occupancy level temperature and humidity for at least five days at 22°.
- Using a hygrometer, verify the sub-floor (plywood) humidity level; it must not exceed 12%. If the humidity level is too high, turn up the heat and open the windows a little, opening them too much can be counter productive as it may let in more humidity.
- Remove skirtings boards and door thresholds.
- Screw the sub-floor securely or over membrane/underlay float. Using a handsaw or skill saw, under cut the bottom of the door frames to the thickness of the floor, in order to slide a hardwood plank beneath the door.
Tools and material required
- Hardwood floor nailer (with rubber mallet) available to hire
- Electric drill and bits
- Tenon-saw, circular saw or handsaw
- Claw hammer
- Measuring tape
- Chalk line and tapping block
Step by step installation
Before you begin it is important to verify the working condition of the hardwood nailer to prevent damage to the planks.
- Using the chalk line, draw a line parallel to 25mm larger than the planks width. Never nail closer than 75mm from the end of the plank.
- Select the planks, lay them out on the floor in the general pattern in which they will be installed. The straightest planks should be used for the first and second rows.
- Always select your planks with care. Those with flaws must be recut.
- Lay the tongue edge of the plank on the guideline, leaving a 15mm space between the groove edge and the starting wall. This expansion space will allow the wood to expand if necessary.
- The first row must be secured to the floor using screw shank flooring nails or pins. Drill holes on the surface of the planks at 25mm from the edge approximately 300mm apart.
- Measure and cut a plank the required length to finish the first row. As the remaining section will be used to start the second row, the plank selected for the first row must be long enough to yield a remaining section of adequate length. Leave a 19mm space between the wall and the plank in each row.
- Start the second row with a plank at least 150mm shorter or longer than the plank used in the first row; this will avoid aligning the joints. Set the plank in place, then nail through the tongue at 45° using the nailer every 250mm. (Try a few hammering tests on a piece of scrap wood to determine the pressure needed to properly drive nail.)
- For best appearance, leave enough distance between the joints by alternating with planks of different lengths to avoid aligning joints.
- The last four or five rows must be installed in the same manner as the first two rows. The use of the hardwood floor nailer is impossible since the last rows are too close to the wall.
- Conceal the nail holes using wax or filler.
A movement gap of 15mm should be provided around the perimeter of the room and at all fixed points. This gap must be left clear and not filled. The gap is concealed either by the skirting board, which is fastened to the wall, or by a small moulding which is fixed to the skirting board not the floor itself. Areas over 50m2 may require additional expansion provision.
2. To Lay an Engineered Floor
Using an engineered floor is simpler than using a solid floor as the material is inherently more stable and generally will go together more easily lending itself to being installed floating or fully bonded. Engineered floors generally, according to manufacturer, arrive on site having been produced in a climate controlled factory, dried to 10% MC and then wrapped in cardboard and polythene so it will not take up humidity before arrival at site. This means they can generally be laid without any period of acclimatisation although in extremely cold weather it would be a good idea to deliver the goods to site a day or 2 before installation.
The relative humidity in the room where installation is going to take place must not exceed 65%. Ensure that the sub-floor is flat, level and dry before installation. Do not unwrap the flooring boards until installation is commenced.
16mm, or thinner engineered wood panels, with a blockboard or plywood core are designed to be laid as floating floors. 18- 22mm thick boards as well as nailing (see above) can also be floated or fully bonded.
Lay an underlay incorporating a moisture barrier on screeds at right angles to the direction of the floor. Lay the first row of boards at a distance of 15mm off the wall and insert spacers. Apply glue to the end and side grooves and tap the boards tightly together using a hammer and a tapping block. Wipe off any excess glue immediately using a damp cloth. Begin a new row using the off-cut from the end board of the previous row. Please note that the boards’ end joints must be staggered by at least 300mm in adjacent rows. At both ends of the room 15mm should be left between the end of the boards and the wall. This gap may need increasing in larger areas. There should also be an expansion gap left at all fixed points.
Fully Bonded or Glue Method
Follow the same preparation procedures and installation principals as above but instead of underlay you a flexible wood adhesive specifically designed for use with wood floors and apply glue to the entire back of the boards and bond them directly to a sound level sub-floor, whether concrete, plywood chipboard or floor boards.
If boards are factory lacquered they require no further finishing but if they are wax oiled or UV oiled we recommend that a second coat of a clear wax oil is applied as the factory finish is generally meant to be a primer coat only. Unfinished boards will require sanding the first sanding is normally done with a large belt sander and the final a rotary, using progressively finer grits, for a smooth finish; the floor can then be filled and finished with 2 coats of a lacquer or wax oil.
If other trades such as decorators or electricians need to work above the floor after it is finished then it is imperative that protective layer is used, this must not be clear polythene and we recommend a corrugated plastic, such as Cordex, which gives adequate protection against dropped tools and paint splashes.
Flooring should never be left outside in the elements. It is hydroscopic and will absorb moisture and therefore shrinks when fitted.
Before laying it is important to locate any services, especially electrical, water and heating systems.
If a water pipe is penetrated by a nail during fitting it will leak and water will be absorbed by the floor and expand causing distortion and, in extreme cases, lifting.