Posts Tagged ‘DIY guide’

Traditional Secret-Nail Fixing of Wood Floors

Jun 10, 2009 DIY tips, bonding, how to, wood flooring

Solid tongued and grooved strip and plank flooring may be installed by secret-nail fixing to suitable wood-based sub-floors such as floorboards, flooring grade chipboard, plywood, or OSB.

In most cases existing decorative hardwood floorcoverings should be removed before the installation of new hardwood flooring.

Environmental Conditions

  • All wet trades must be thoroughly dry before flooring materials are delivered to site.
  • Maintain suitable ambient humidity 40 to 60% RH. (Monitor with a hygrometer)
  • If necessary employ a domestic humidifier or dehumidifier to maintain suitable humidity.
  • Ambient temperature to be 18 to 22 Celsius during acclimatisation and installation.

Basic Requirements of the Sub-floor

  • Wooden sub-floors must not be installed as a floating floor, but be securely fixed (e.g. floorboards to joist).
  • Ensure all sub-floors are sound, free from decay, and of load-bearing strength.
  • Wood based sub-floor materials must not be more than 2% higher in moisture content than the new wood flooring materials being installed.

Tip

  • Flooring must not be exposed to artificial heat sources from the sub-floor. Hot water pipes beneath suspended wood floors can cause excess heat and should be thoroughly insulated. Floor temperature must not exceed 24 Celsius.

Evenness of sub-floor

  • All wood based sub-floors must be even to within 2mm over any 2 lineal meter area.
  • In order to achieve the necessary degree of evenness, traditional softwood floor boarded sub-floors typically require a WBP plywood covering to be securely fastened (preferably by screwing) to the floorboards before secret-nail fixing new wood flooring. (Plywood must also be of suitable moisture conditions. See ‘Basic Requirements of the sub-floor’ above.
  • It is recommended that flooring grade chipboard, OSB & old floorboards are first covered with WBP plywood which is securely fastened to the sub-floor before secret-nail fixing new wood flooring, as this will hold nails well and help avoid squeaking.

Suspended wood based sub-floors at ‘ground level’

  • Voids beneath suspended wood based sub-floor on ground level must be well ventilated to avoid high humidity in the sub-floor void.
  • First lay a building paper moisture barrier (e.g. Sisalkraft Moistop), over the existing sub-floor overlapping joins by 100mm and taping with a waterproof tape.
  • Then install a WBP ply layer, securely fixing through the building paper to the sub-floor.

Secret-Nail Fixing

  • When fixing flooring solely by secret-nailing, we recommend that a building paper moisture barrier (e.g. Sisalkraft Moist Stop), is laid over the existing sub-floor overlapping joins by 100mm and taping with a waterproof tape.
  • Boards of 150mm or wider may be secured with adhesive in addition to secret nail fixing.
  • When using the combination of secret-nailing and adhesive, a moisture barrier building paper is first laid over the existing wood based sub-floor, followed by WBP ply. The WBP ply is securely fixed through the building paper into the wood based sub-floor. Hardwood flooring is then bonded to – and nailed through the ply base into the existing wood based sub-floor.
  • Secret-nail fixing is achieved using a purpose made floor nailer (e.g. Portanailer, Primatech etc) which are used with purpose made serrated galvanised floor nails of varying length depending on the thickness of flooring being installed. (18-20mm flooring thickness = 50mm nail).
  • Tongue and groove flooring is secret-nailed (also called ‘blind nailed’) fixed through the tongue at approx 45 degrees into the sub-floor at intervals of 200 to 250mm.
  • Nails are placed 40 to 60mm to each end of each boards, with not less than two nail fixings per board.
  • In addition to secret-nailing on the tongue side, starting rows one and two are face nailed or can alternatively bonded to sub-floor to secure the groove side that is not linked into an adjoining tongue
  • If starting from a centre line using biscuit tongues, the two centre boards may be face nailed or preferably bonded to the sub-floor using a flexible adhesive.

Provision for expansion

  • As a guide only allow a minimum 15mm expansion wherever the floor meets obstacles including perimeters walls, structural supports, hearths etc.
  • Create additional expansion breaks in doorways using suitable profiles such as T-section thresholds / transition strips.
  • Create additional expansion breaks in large floors.
  • Where possible install flooring so that planks, strips run parallel to the longest walls, so the direction of greatest potential expansion (i.e. across the grain) does not coincide with the direction of greatest dimension, esp. in large floors.
  • The precise combined provision for expansion must be judged by the installer taking into account environmental humidity, moisture content of wood at time of installation, timber specie and size of the floor.

For more information see our wood flooring site.

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Bonding to Wood based Sub-floors

Jun 10, 2009 DIY tips, bonding, how to, wood flooring

Wood-based sub-floors are materials such as floorboards, flooring grade chipboard, plywood, or OSB.

Existing hardwood floor coverings should be removed before installation of new hardwood floors.

Environmental Conditions

  • All wet trades must be thoroughly dry before flooring materials are delivered to site.
  • Maintain suitable ambient humidity 40 to 60% RH. (Monitor with a hygrometer)
  • If necessary employ a domestic humidifier / dehumidifier to maintain suitable conditions.

Moisture condition of Wood based sub-floors

  • Ensure that wood based sub-floor materials are not > 2% higher in moisture than the new wood flooring materials being installed.

Suspended wood based sub-floors at ground level

  • Voids beneath suspended wood based sub-floor on ground level must be well ventilated to avoid high humidity in the sub-floor void.
  • First lay a building paper moisture barrier (e.g. Sisalkraft Moistop), over the existing sub-floor overlapping joins by 100mm and taping with a waterproof tape.
  • Then install a WBP ply layer, securely fixing through the building paper to the sub-floor.

Soundness of sub-floors

  • Ensure all sub-floors are sound, of load-bearing strength and free from contaminants that may impede adhesion. (Note: If sub-floors are contaminated or affected by adhesive residues seek further advice).

Evenness of sub-floor

  • In order to achieve satisfactory contact between wood flooring and adhesive, sub-floors must be even to within 2mm over any 2 lineal meter area.
  • Floor boarded sub-floors typically require a WBP plywood covering to be securely fastened to the floorboards before adhesive fixing new wood flooring.
  • It is recommended that flooring grade chipboard, OSB & old floorboards are first covered with WBP plywood which is securely fastened to the sub-floor before adhesive fixing new wood flooring to protect against surface contaminants that may impede adhesion.

Adhesive bonding of wood flooring to wood based sub-floor

  • Use a purpose made, permanently flexible adhesive such as 1-part polyurethane, when adhesive fixing.
  • Always use the trowel type recommended by the adhesive manufacturer for the type of flooring being installed (e.g. solid plank, strip, woodblock, engineered plank etc).
  • Replace worn trowels.
  • Ensure full contact between the underside of the flooring element and adhesive.
  • Any adhesive that that comes into contact with the face of the boards must be cleaned off whilst wet, as residues are not removable when cured.

Provision for expansion

  • As a guide only allow a minimum 15mm expansion wherever the floor meets obstacles including perimeters walls, structural supports, hearths etc.
  • Create additional expansion breaks in doorways using suitable profiles such as T-section thresholds or transition strips.
  • Create additional expansion breaks in large floors.
  • Where possible install flooring so that planks, strips run parallel to the longest walls, so the direction of greatest potential expansion (i.e. across the grain) does not coincide with the direction of greatest dimension, esp. in large floors.
  • The precise combined provision for expansion must be judged by the installer taking into account environmental humidity, moisture content of wood at time of installation, timber specie and size of the floor.

You can contact us for more information at www.floorcraft.uk.com or call us on 01252 372227/07970 491384 ask for Gavin Winder (we are based in Farnborough, Hampshire, UK and stock all of the above mentioned wood flooring adhesives, latex, underlays etc).

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How To Install A Solid Wood Floor

May 5, 2009 DIY tips, how to, solid wood floors, wood flooring

If you have purchased a solid wood floor then there a variety of ways that theses can be fitted.  The one thing to remember is that solid floors cannot be floated under any circumstances.  There are many companies that will tell you it is suitable, but in my experience it will eventually fail and start to cup and curl.  This is because solid wood is prone to a large amount of expansion, these types of floor need to be directly bonded to the sub floor by either nailing or gluing down.

If your sub floor is a screed or concrete type then you should first check for any moisture or dampness within the slab to do this use a moisture meter with concrete probe, we use a Tramex meter. If you do not have access to a moisture meter and are unable to ascertain weather the slab has a damp problem, then for piece of mind it is a good idea to apply an epoxy barrier.  We use and recommend Bona R410, to act as a moisture barrier you will need to apply two coats with a roller and allow 24hrs between coats.  You should always apply your moisture barrier from wall to wall and take it approx 60mm up the wall as well to create a complete seal.  If your floor is damp to the touch then a moisture barrier will not adhere to the sub floor, in this case seek professional advice (you may have a split pipe or a high water table coupled with a defective slab).

If you choose to install the floor by gluing it down, then you must ensure that the slab is completely level and flat.  To do this place a 1800mm spirit level on the floor, if there are gaps greater than 2mm over 800mm  between  level and the floor, then the floor will need latex levelling.

When you have a level surface you must now undercut all of the door frames, nule posts (nule posts should only be undercut by 10mm anymore will make the post unstable) and architraves.  It is very important do to this as it enables you to archive a seamless finish; it also allows an expansion area for the timber.  We do this using an undercut saw, which is basically an upside down circular saw with a height adjustable sole plate, this allows the correct height equal to that of the finished floor level to be undercut and removed.  If you do not have an undercut saw then the best alternative would be to use a small piece of flooring, this will give you the correct height you can now undercut this using a small handsaw resting on top of the flooring.   Make sure you only undercut as far as the flooring is going to go i.e. if your floor finishes at a threshold to a kitchen for example, only undercut up to the end of the door stops.  Remember you must always leave 25-30mm gap between an existing floor i.e. tiles and your new floor to allow a graduating door bar to be fitted.

Use a very sharp chisel to remove the piece of wood that you have undercut/frame by gently chiselling away at it bit by bit, this does work but takes care and time.  When you have under-cut fully use a narrow chisel (narrower than the cut you have made) to ‘knock out’ the pieces of frame/wood,  make sure you have removed all that you can, the more you remove now the easier it will be to install the floor later.

You are now ready to start installing your floor….

First decide on the direction that you want the floor to run in, bear these few points in mind before you make your decision.  Try to start from the longest, straightest wall, ideally form the door way side. If there is no doorway on the longest wall but there is a radiator or pipes coming out of the floor then start from this wall (it is much easier to do the radiator cuts or doorway cuts on the first row than it is on the last).   Do not attempt to start the flooring with a broken line i.e. trying to go round a fire place or large obstacle, we do sometimes do this but it takes a bit of practice and patience to get it right.

There are two ways in which you can fit solid wood flooring, (the method of use will be dependent on type of sub floor you have);

  1. By secret nailing directly to joists or at 90 degrees to existing floor boards using a Porta nailer or compressed air nailer.  If you choose the nailing route there are a few things you need to consider. Firstly  make sure your nails do not project more than 2mm below the sub floor you are nailing into, porta nails are available in 1½ inch 1¾  inch and 2 inch. The length is important because you do not want to hit any pipes or cables that may be directly underneath the floor.  Secondly you should be aware that you will have to face nail i.e. through the top of the board for the first and last two rows, as the angled porta nailer will not fit in.  Thirdly floors that have been nailed down are prone to squeaking, this probably won’t happen for many years but when it does the only way to resolve it is to nail through the face of the board.  Obviously you run the risk of hitting a pipe or cable in doing this; however this can be avoided if you draw a floor plan when installing the floor.
  2. By gluing directly to a concrete or ply/chipboard floor.  Few things to consider here, personally if the sub floor was ply or chipboard then I would secret nail it.  If you nail into chipboard then you will have to put a fixing every 150mm.  This is because chipboard is a particle board, as the nail goes in it almost causes the back of the chipboard to explode out; we double the amount of fixings we put in to compensate for this.  A Couple of points to be aware of when gluing.  Always use glue that is recommended for the installation of the board that you have purchased, for example Bona S760 is a solvent based glue and is only suitable for boards up to 150mm in width.  For boards over this use either Bona R850 or Sika T54/T52.Moisture is a huge issue when you glue a floor directly to a concrete slab, this is because wood is hydroscopic meaning that it will adapt to its environment by absorbing moisture.  If you suspect moisture is present always use a meter to check the levels, levels for fitting directly onto concrete should be below 25% RH.  If the levels are above this but below 75% RH then a Epoxy barrier can be applied, see previous blog post.

    Flooring adhesives are split into 3 categories:
    -  Firstly there are solvent based glues, these tend to be the cheapest (expect to pay £50 for 13kg tub) and quickest drying but have limited uses i.e. they can only be used on boards with a width less than 150mm and not in the presence of under floor heating.
    - Secondly you have non solvent adhesive, these are the most commonly used, this is because they have a longer ‘open time’ are easier to trowel out and work with.  They are generally a lot more expensive than solvent based, expect to pay £80 for 15kg tub (1kg of adhesive will cover 1sqm of floor), however they are  more versatile and can be used to bond boards down up to 220mm wide.
    - Thirdly there is non solvent gun applied adhesive.  This is the same as above but is used in bulk guns to apply adhesive on to Sika silent layer, this is an underlay mat used to take up small deviations in a floor as well as adding insulation and the use of less glue.  The mat layer has small holes cut into it where the adhesive is dispensed into, we use either Bona 600cc sausages or Sika T2, both are very similar, expect to pay £12.00 per sausage and £35.00 for the dispensing gun (one sausage will cover approx 1-1.5sqm).

    First trowel your glue out using a flooring trowel.  Lay the first line of boards down with the groove in the board facing the wall, ensure that you have 80% glue coverage on the back of the boards and no hollow spots.  When you get to the end of the line you will need to cut the final board in, this can be easily measured as follows; If you have a tongue on the board that is laid on the floor, you need to place the final board with its groove end against the wall you are going to finish on.  Leave a 10mm gap between the groove end and the wall; now mark off what is to be cut off by marking a line on this board in line with the end of the board that is on the floor. I know it sounds confusing but it really isn’t too difficult, if you are unsure use a tape measure to check your measurement and then use the off cut to start the next row.

When you are gluing floors it sometimes necessary to strap the floor with compression straps to ensure that all the gaps in between the boards are closed up, these normally only need to be used for the first three or four rows, after this the flooring should be all aligned properly.

It is also a good idea to leave weight on the floor that you have just laid to ensure that it bonds to the sub floor properly; you can use the flooring that you have not laid as weight, or any un-opened tubs of flooring adhesive.

Be sure to remove any spillages of adhesive before they dry, this particularly important when fitting an oiled floor using Sika T54.  Sika is a very good adhesive but incredibly difficult to remove when dry,  it is so strong that if you try to remove a board when the glue has cured it will either leave large splinters of wood on the floor or bring the screed/latex up with it.  It for this reason that as a fitter I no longer use Sika T54, we now use Bona R850, this adhesive can be removed with water when wet and with UPVC solvent cleaner when dry.  Although not as strong as Sika, it still has plenty of ‘grab’ and if you do need to remove a board or re-position it normally it will leave the screed/latex intact.

When you get to the last three rows make sure you have troweld all your adhesive out right up to the edge of the wall, this will make it easier when fitting the last two rows as you will not be able to fit a trowel in.  As with all the boards measure twice cut once, there is nothing worse than trying to re-cut a board when it is covered in glue.

Once finished leave some weight on the last few rows you have just laid.  Leave all your expansion wedges in as well as adding some behind the last row you laid to ensure that the floor does not move when drying.  Leave the floor un-trafficked for 24hrs then go in and remove all the expansion wedges, stand back and admire your hard work, knowing that because you followed my guide you will have a beautifully fitted wood floor to admire for many years to come.

For any more information please contact Gavin at Floorcraft in Farnborough, UK (+44 (0)1252 372227) or visit us at  www.floorcraft.uk.com

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How To Install Floating Wood Floors

Mar 16, 2009 DIY tips, floating floors, how to, wood flooring

First and foremost you must ensure that the type of flooring you have purchased is suitable for a floating installation, if the floor is a solid wood type then it is not suitable for floating, this is because solid wood is prone to a large amount of expansion, these types of floor need to be directly bonded to the sub floor by either nailing or gluing down.

The only types of wood floors that can be floated are those that are engineered, this flooring is made by bonding a veneer of wood, often called a ‘stave’ to multi layer ply wood.  This creates a multi directional structure, which makes it very stable, and therefore suitable for floating installation.

Now you have ensured that your flooring is suitable for this type of installation, you must ensure that your subfloor is suitable and ready to accept your flooring.

With a floating floor your sub floor can be timber, concrete, or screed or a mixture of all three,  you have to ensure that your sub floor is level and flat i.e. no deviations greater than plus or minus 2mm over 1.5m.

If the sub floor does need levelling, then this can be done using a variety of methods.  If you have floor boards which are cupped and crowned i.e convexed or concaved, then you  can ‘ply over’ these using 3mm ply or hardboard.  The ply or hardboard should be stapled down using 18 gauge 18mm staples  or tacked down using annular ring shank nails no longer than 20mm.  The depth of these fixings is very important as if they too long then there is a chance you may hit a water/gas pipe, as these are sometimes notched into the joists underneath the floor boards.

If they are very uneven you could use a thicker sheet of ply anywhere between 9 and 18mm, obviously the thicker sheet you use then the higher finished floor level will be.

If the floor is still un-level after installing the ply then level this out using a latex levelling compound, this must be a two part compound and suitable for using over timber, we normally use Adtitex yellow bag and black bottle.  You must always prime the timber which is to be latexed with Bal R1131 or Arditex acrylic primer.

When you have a level surface you must now undercut all of the door frames, nule posts (nule posts should only be undercut by 10mm anymore will make the post unstable) and architraves.  It is very important do to this as it enables you to archive a seamless finish; it also allows an expansion area for the timber.  We do this using an undercut saw, which is basically an upside down circular saw with a height adjustable sole plate, this allows the correct height equal to that of the finished floor level to be undercut and removed.  If you do not have a undercut saw then the best alternative would be to use a small piece of flooring on top a piece of underlay, this will give you the correct height you can now undercut this using a small handsaw resting on top of the flooring and underlay.   Make sure you only undercut as far as the flooring is going to go i.e. if your floor finishes at a threshold to a kitchen for example, only undercut up to the end of the door stops.  Remember you must always leave 25-30mm gap between an existing floor i.e. tiles and your new floor to allow a graduating door bar to be fitted.

You may find that when you have undercut using a hand saw or undercut saw, that there is still a piece of wood /frame that you cannot cut through.  Really the only way to get this last piece is to use a tool called a ‘Fein Multi Master’, this tool has a reciprocating narrow blade which will enable you to get in the tightest of spaces to remove the last piece of timber.  Obviously if you are only going to be fitting your own floor and not doing this as a job, then the investment of £180 for one of these tools would probably not be worth it.  In this case you could use a very sharp chisel to remove the last piece of wood/frame by gently chiselling away at it bit by bit, this does work but takes care and time.  When you have under-cut fully use a narrow chisel (narrower than the cut you have made) to ‘knock out’ the pieces of frame/wood,  make sure you have removed all that you can, the more you remove now the easier it will be to install the floor later.

You are now ready to underlay your floor, simply roll out the underlay across the floor making sure it goes right up to the edges but does not’ flap up’ the edges.  You do not need to put underlay underneath the frames that you have cut out or under any nule posts, you will find that this will get in the way when trying to install the floor.

On a screed or concrete floor your underlay will need a DPM (damp proof membrane), most modern underlay’s such as Treadaire Boardwalk or Timbermate Excel have a built in damp proof membrane, we would recommend that you use one of these,  any breaks or joins should be fully sealed with vapour tape or Duck tape.

If you have purchased an underlay without a built in underlay, then you will need to lay a separate DPM, this should be a 1000 gauge polythene  with any breaks fully sealed with vapour taped/Duck tape.

On  a timber suspended floor you do not need a DPM nor do you have to fully tape the underlay together, it just be taped at approx 300mm intervals, just enough to hold it together whilst the floor is fitted.

Now you have installed your underlay you are now ready to start fitting your floor.  First indentify the longest straightest wall, your floor should always run with the longest wall.   If you have radiators in the room then you try to start from these as it easier to cut around radiator pipes now than it is on the last line.

Lay the first line of boards down with the groove in the board facing the wall, when you get to the end of the line you will need to cut the final board in, this can be easily measured as follows; If you have a tongue on the board that is laid on the floor, you need to place the final board with its end groove against the wall you are going to finish on.  Leave a 10mm gap between the groove end and the wall; now mark of what is to be cut off by marking a line on this board in line with the end of the board that is on the floor. I know it sounds confusing but it really isn’t too difficult, if you are unsure use a tape measure to check your measurement and then use the off cut to start the next row.

When you have laid two complete rows, space the floor from the wall allowing approx 10mm expansion gap, use plastic spacers (available from most DIY stores).  There may places where this is greater or lesser than 10mm,  don’t worry too much about this, as long as there is no point which is smaller than 5mm or greater than the thickness of the skirting or beading which you are going to use to cover the expansion gap.  If you are covering a very wide room then you do need to be quite strict with the expansion gap.

Carry on laying the floor keeping the expansion gap all around the room, stagger all the joins by at least 300mm on every row, remember to be vigilant with the boards that you install, any particularly dark or oddly grained boards should be discarded or used in inconspicuous place such as under stairs or as the last board at the edge of the room.

Remember to leave approx 35mm between the edge of the new wood floor and any existing floor to allow for a door bar.  The new wood floor should finish just inside the door stops (approx 5mm). This is so that the door bar fits underneath the door and you cannot see the flooring from the other rooms.  When all the doors are closed surrounding the floor you have just fitted, you should not be able to see any of the other floors coming from the other rooms.

You should now have your entire floor fitted, the only thing that remains to do is to remove your installation wedges (ideally these should be left in place for 12 hours so that the glue can set), once removed you either fit your skirtings or beading.

For any more information please contact Gavin at Floorcraft in Farnborough, UK (+44 (0)1252 372227) or visit us at  www.floorcraft.uk.com

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