Floors and Ceilings

In the open hall-house of the medieval period, the roof over the hall provided an important opportunity for display, and exposed roof timbers could be quite ornate. Widespread use of enclosed fireplaces and chimneys in the sixteenth century made an overall upper floor possible in houses, giving ceilings to ground floor rooms. Ceilings then became areas for a degree of display. Where carpentry traditions were strong, a framework of beams supporting joists could be given decorative treatment using moulded detail matched to the status of different rooms.

Although there are some fine examples of plaster ceilings from the late sixteenth century, exposed timber-work prevailed until at least the late seventeenth century (and later still in vernacular buildings — farmhouses and cottages). Decorative plasterwork was an expensive refinement, and was generally confined to the principal rooms of higher status houses. Some lowly vernacular houses emulated plaster ceilings by using calico stretched beneath the joists.

Plaster ceilings are traditionally made of lime plaster, which is applied in three coats, with animal hair mixed into the first two. The plaster is applied to a framework of wooden laths, which are nailed to the joists or rafters above. The first coat of plaster is squeezed into the gaps between the laths to produce nibs or keys, which help to hold the ceiling in place. From the nineteenth century, gypsum was often added to plaster to help speed up the setting time.

Ceilings in the principal rooms of high-quality, sixteenth-century houses were often embellished with hand-modelled plaster decorations. Plasterwork based on classical motifs, including acanthus leaves, egg and dart, fluting and Greek-key design, were particularly popular during the eighteenth century, setting off the generous proportions of the rooms to good effect. However, it was slow to produce, requiring a high degree of skill, and was therefore expensive. Cornices were run in situ and decorative friezes and ceiling roses were built up in stages using cast or hand-modelled plaster ornaments. Papier mâché was also used for cast mouldings, with the advantage that it was a lightweight material.

The introduction of fibrous plaster mouldings from the mid-nineteenth century revolutionized interior design. This technique allowed the rapid and cheap mass production of complete highly decorative pieces, which were transported to the building and fixed in place. They were produced in moulds using gypsum plaster reinforced with scrim — a course, open weave cloth — with a backing of laths and ribs to strength the piece and provide fixing points. Even quite ordinary buildings were now sometimes given highly ornamental ceilings and friezes. However, the technique really reached its peak in the flamboyant decoration of theatres and music halls.

The joists to which the ceiling was fixed also supported the boards of the upper floor: as a rule of thumb, the earlier the floor, the wider the boards. Oak or elm was commonly used until machine-sawn pine boards became widely available in the nineteenth century. The treatment of ground floorswas more varied, and flagstones or, from the nineteenth century, slate slabs and quarry tiles are common domestic flooring materials throughout Wales. There are some examples of highly localized traditions of flooring. ‘Pitched’ or cobbled floors made from beach or river pebbles set vertically in geometric patterns are a feature of some Montgomeryshire houses, and are also found along the western seaboard, such as in Llanon in Ceredigion. In parts of Glamorgan, there are mortared floors of lime and sand. The humbler vernacular buildings made do with what was most widely available, and earth floors were commonplace.

What to look for: 

Damp or salt-stained flagstone, pitched stone, or tile floors

Suggested action: 

Check for and eliminate any obvious sources of moisture, such as raised external ground levels or blocked drains. If the damp is due to condensation, increase ventilation.

Old flagstone, pitched stone, and tile floors are often laid directly onto the earth or on a bed of permeable material, which can make them cold and prone to condensation. However, any attempt to seal stone or tiled floors can create further problems by trapping in moisture that would otherwise simply evaporate. Lifting the flooring to install a damp-proof membrane, for example, can force moisture into the walls where it can potentially cause more serious problems.

Allow the flooring to breathe by avoiding cement pointing, waxes and other sealants. Also avoid impervious finishes, including vinyl flooring and foam- or rubber-backed carpets. If condensation is a problem, try to control humidity levels in the building and increase the amount of ventilation. Salt staining is generally harmless, but treat mildew and other organic growths with a dilute bleach solution or biocide, if necessary.

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What to look for: 

Damp or decay in suspended timber floors

Suggested action: 

Remove any vegetation or other obstructions blocking external underfloor vents, grilles or airbricks and ensure that air can circulate freely beneath the floor.

Do not be tempted to block the ventilation to reduce drafts as this can lead to a build up of moisture, creating the ideal conditions for wet and dry rots to develop. If you intend to insulate the floor, install the insulation between the joists, ensuring that there is a good through flow of air beneath. Draft proofing can also be installed between the floorboards and skirting boards if there is a gap.

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What to look for: 

Floorboards — splits or gaps; squeaks

Suggested action: 

Look for any change in the condition of the floor and refix loose boards and fill gaps if necessary.

Before the eighteenth century, floorboards were often made of oak or elm, and of irregular widths of between 8 and 10 inches (200–250mm). They were sawn and shaped by hand, and laid to butt up against the next board before being nailed onto the joists.

Imported pine began to replace hardwood from the eighteenth century, but the narrow tongue and groove boards of uniform width, which are still used today, only became available from the early part of the nineteenth century as a result of mechanization. If you are replacing or patching a floor, it is important to choose the correct type of timber and size of floorboard to suit the age of your building. These historical differences are important and the right choice of material will greatly enhance the appearance and authenticity of a room. Try to find reclaimed boards to match, and when patching, try to match the pattern and direction of grain.

Wood naturally expands as it absorbs moisture and contracts as it dries out again. This can lead to boards splitting or gaps opening up between them over time. Whilst it is sometimes suggested that floors should be lifted and re-laid, this can cause unnecessary damage and is rarely justified. Similarly, worn boards add character to a building and they should only be replaced if they are structurally unsound.

Warped or loose floorboards can squeak as they rub against a nail or adjacent board. This can often be eased by driving the nail deeper into the timber using a nail punch. If the problem recurs, you may need to replace the nail with a longer one to improve the grip.

Splits can be caused by shrinkage or damage when the board was nailed down. This can often be a problem when boards are lifted in order to install new services. If the boards must be lifted for any reason, it may be preferable to screw them back down, rather than nailing them, particularly if the disturbance could damage a fragile or decorative plaster ceiling below. Use stainless steel counter-sunk screws set deeply into the board and fill the recess with wood filler or a plug of matching wood.

Small gaps between the boards are not usually a problem, but they can be filled if desired with flexible wood filler. Larger gaps can be filled using tapered slivers of matching wood. Scrape the edges of the boards to clean out the gap and the glue the sliver into position using wood glue.

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What to look for: 

Parquet floors — loose blocks

Suggested action: 

Check for loose blocks and if necessary refix using flooring adhesive.

Parquet flooring was particularly popular during the late Victorian and Edwardian eras. It consists of oblong blocks of high-quality timber, which were usually laid on a bed of hot bitumen. A variety of timber species and block patterns were used, such as herringbone and basket pattern.

Parquet flooring is susceptible to damage if it gets damp. If the blocks are coming loose, check whether there is a leak and eliminate the problem. If they are damp, dry the blocks out under weights to stop them warping. Remove any dirt and debris from the recess and refix the blocks using flooring adhesive. Damaged surfaces may need to be sanded and refinished.

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What to look for: 

Dirty or deteriorating timber floor finishes

Suggested action: 

Check for signs of wear and tear, and, depending on the type of finish, treat the floor if necessary.

Sweep timber floors regularly to remove dirt and grit that could scratch the surface. If necessary, unfinished, oiled or varnished floors may be washed sparingly with a minimum amount of soapy water. Rinse with a well-wrung out mop and dry with a clean cloth. Do not wash a waxed floor. Instead, use a liquid cleaning wax in accordance with the manufacturer’s instructions.

An old floor of wide oak or elm boards adds considerable richness to any room. Minor damage, including scuffs and scratches, is inevitable and should be seen as part of the patination, adding character to the room. Historic floorboards should never be sanded as the process will remove this patina, leaving a dull and lifeless surface. If the timber has been attacked by woodworm at any time, it can also expose the unsightly tunnels that are normally hidden just below the surface.

If a new finish must be given to an old floor, modern polyurethane varnishes should be avoided, particularly on oak or elm boards, as they do not have the same mellow appearance as a traditional oil or wax floor polish. They are also difficult to remove; they tend to yellow with age and can chip easily. Linseed oil is also best avoided as it attracts the dirt and darkens with age.

Pine boards were sometimes painted or stencilled, and these finishes should be retained.

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What to look for: 

Moisture staining on joists and floorboards; signs of softness or decay, fungal growth, a musty smell or a distorted paint finish.

Suggested action: 

Check joists and floorboards, particularly those in contact with masonry, and seek guidance from a specialist timber decay consultant if signs of decay or fungal growth are found.

Check that timbers feel dry to the touch, particularly where they abut or are built into external walls. Gently push the tip of a penknife or similar tool into the wood to check that the timber is sound.

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What to look for: 

Signs of active beetle infestation in joists and floorboards (new flight holes and fine wood dust, known as ‘frass,’ on adjacent surfaces).

Suggested action: 

Carefully check joists and floorboards and seek guidance from a specialist timber decay consultant if any signs of beetle infestation are found.

Fungus breaks down the chemicals in wood and this can encourage beetle infestation. The possibility of both problems being present should therefore be considered.

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What to look for: 

Distorted, split or fractured beams; sagging timber floors.

Suggested action: 

If any signs of structural movement have recently appeared, arrange for investigation by a structural engineer.

Distorted beams and sagging floors may simply be the result of settlement that occurred shortly after the building was constructed, but any newly damaged beams or other signs of recent or continuing movement should always be investigated by a structural engineer.

Possible causes include decay of the joist ends due to damp penetrating through the wall, or movement of the structure causing the timbers to lose their bearing on the masonry. Another common problem is weakening of the beams as a result of cutting or boring through them to accommodate new pipes, wires and ducts.

While timbers in historic buildings may not meet the standard sizes set out currently by the Building Regulations, this is not usually a cause for concern and it should not be assumed that ‘undersized’ beams need to be replaced. The building has survived up until this point and alterations should be made only where there is a problem and remedial action is absolutely necessary. The introduction of a new use into a building can, however, alter the stresses that it must withstand. The conversion of an attic into habitable rooms, or a change of use of upper floors from domestic to office use, for example, can substantially increase the weight on the floors and supporting beams.

Where additional strengthening and repairs are necessary, the work should be carried out in an unobtrusive manner retaining as much of the original timber as possible. For example, weakened beams can often be left in place and strengthened using steel plates, whilst rotten joist ends can be replaced by splicing in new sections of matching timber, rather than replacing the whole beam.

Undulating, sloping or bouncy floors are almost inevitable in historic buildings and are part of their charm. Do not attempt to level floors unless it is structurally necessary.

What to look for: 

Damp or stained plaster ceilings

Suggested action: 

Check the building systematically inside and out to find the source of the damp. Eliminate the problem as soon as possible.

Water may travel some distance before it appears as a patch of damp on a ceiling. Be sure, therefore, to check your building thoroughly to identify the source of moisture. You may need to check:

- roofs 

- chimneys 

- rainwater disposal systems 

- walls 

- utilities 

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What to look for: 

Sagging or cracked lime plaster ceilings

Suggested action: 

Check ceilings for signs of cracks, sagging or movement. Repair minor cracks with a flexible filler, but take advice if more substantial changes occur.

Cracks between the ceiling plaster and cornice, or between the ceiling and wall are often be due to slight movements that naturally occur in historic buildings or from uneven shrinkage of the plaster. Such cracks are to be expected and are not necessarily cause for concern. They can easily be repaired using a flexible filler. However, larger cracks between the edge of the ceiling and wall can suggest structural movement, which should be investigated by a structural engineer.

Sagging plaster or cracks across the ceiling can occur for a number of reasons — rot or beetle infestation of the timber laths, rusting of the fixing nails, breaking of the plaster keys or movement or failure of the floor joists. Unless the problem is minor, consult a building surveyor or architect for advice on suitable repairs.

Ceilings should always be repaired if possible, particularly if they are early or decorative examples. Even a simple plaster cornice is an important historical feature, which can add a touch of elegance and style to an otherwise plain room. Ceilings should not be removed or replaced unless absolutely necessary. They can be propped from below while structural strengthening or other repairs are carried out and even badly sagging ceilings can usually be reattached to the supporting structure.

Where replacement is absolutely necessary, the work should be carried out on a like-for-like basis, taking care to replicate the plaster mix and techniques used. Plasterboard does not have the same soft and natural appearance as a lath and plaster ceiling, and is not a suitable alternative for a historic building. Similarly, modern gypsum plasters have waterproofing agents added, which prevent them from breathing, and they are not as flexible as lime plaster. These are important qualities for any building constructed using traditional building techniques, and modern gypsum plaster is therefore best avoided.

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What to look for: 

Plaster ceilings — Wear or deterioration in the decorative finish

Suggested action: 

Check for signs of deterioration and redecorate as necessary using a breathable finish.

Although limewash is often thought of as an exterior finish, it was also used extensively for interiors up until the eighteenth century and later for vernacular buildings. Limewash was replaced by soft distemper, which was the traditional finish for decorative ceilings before the introduction of modern emulsion paints.

The delicate details of decorative mouldings can become completely clogged up and obscured by successive layers of paint. Nevertheless, whilst it may be desirable to remove these coatings for aesthetic reasons to return the plasterwork to its original crisp appearance, this must be balanced against the loss of earlier decorative colour schemes. These provide important evidence about the history of the building and changing fashions.

Although chemical paint strippers suitable for use on plasterwork are available and other techniques may be acceptable, the removal of paint is a painstaking process and it is all too easy to damage the underlying material. As a consequence, it is job that is best left to an experienced conservator.

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What to look for: 

Match boarding — Damp or stained boards, signs of rot or beetle infestation

Suggested action: 

Check the building systematically inside and out to find the source of the damp. Eliminate the problem as soon as possible.

Just as pitch pine match boarding was frequently used to clad stud partition walls in cottages during the nineteenth century, it was commonly used for ceilings in attic rooms. With attic ceilings it is particularly important to ensure that the roof covering is sound and to deal with any signs of water penetration as quickly as possible in order to minimize damage. If there signs of decay or beetle infestation are found, take advice from specialist timber decay consultant.

Water may travel some distance before it appears as a patch of damp on a ceiling. Be sure, therefore, to check your building thoroughly to identify the source of moisture. You may need to check:

- roofs

- chimneys

- rainwater disposal systems 

- walls 

- utilities