Home maintenance

NOTE: SANS 10062 contains fixing instructions for the fixing of different types of roofing. This national standard is available from the SABS.

The pitch indicated in Tables 1 and 2 are minimums. In addition to these, sheeted roofs in category 1 buildings that don’t have hips and valleys, may have a slope of 5 degrees, as long as all the end laps are sealed and have a lap of at least 250 mm. The slope of any valleys in the roof should then be no less than 11 degrees.

If tiles are laid at a pitch of 30 degrees they must (in terms of the SANS) be tested in a rig as specified in SANS 542.

The relative humidity must be maintained at a minimum of 70% during the test, and droplets should not form on the underside of the roof. It is a little different for category 1 buildings – rather than droplets forming (or rather not forming) – the test must show that water doesn’t flow down the inside of the tiles. In other words the roof MUST be waterproof!

Sheeted roofs should be tested in accordance with ASTM E 1646 to check that they don’t leak. There must be no dripping of water onto the ceiling or floor of category 1 buildings.

All tiled and sheeted roof coverings must be installed in accordance with the manufacturer’s instructions and/or by workers with the correct skills.

Thatched roofs should be installed according to SANS 10407. The required thickness of the thatch is shown in Table 3 (above).

All roofs with a pitch less than 26 degrees or more than 45 degrees, and all roofs in coastal areas (to a distance of 30 km from the sea) should have an undertile membrane that is loose-laid so that water can drain between the rafters.

If an undertile membrane is properly laid it will provide a very effective, impermeable barrier against wind-driven rain and dust. For this reason the SANS states that underlays should be provided for all slate and tiled roofs, no matter what the pitch (or slope), and where ceilings are not installed.

The manufacturers’ instructions must be followed carefully for tiles, slates and shingles.

1.7 Roof upkeep
To ensure that your roof will serve it’s purpose you need to do the following tasks regularly.

1) Keep the roof debris free. The accumulation of leaves and dust will leads to damp places on your roof. This will cause rust and mold forming and your roof will form rust spot as well as mold growth.

2) Gutters needs to be clean, free of any blockages. Water needs to be drained from the roof fast, standing water causes rust and the growth of mold.

3) Repair any small leaks or replace cracked roof tiles as soon as possible. A leaking roof, even very small holes, will damage your ceilings and cost you money.

4) Repair your roof where you see standing water. Pools of standing water on your roof will safer in and cause expensive damages.

5) Fasteners on your roof are lose. Lose fasteners causes water entry and your roof may be blown off by the wind.

6) Check for rotten beams in your roof. Beams leans to the strength of your roof’s construction. When rotten it may lead to the collapse of the structure.

7) Make sure all fascia boards in place. Fascia boards protects the side of your roof against the rain. the lack thereof will lead to water entering your roof and causes expensive replacement costs down the line

8) Check for membranes that are crack or otherwise damaged. Cracked/damaged membrane do need to be remove and replaced, if not, you will experience rain damage on your roof. That will cost you dearly.

9) Be on the lookout for broken, cracked or missing tiles. When these tiles are not replaced you will have to pay more for repairs later on.

10) Check for insufficient nock and valleys. This will cause for water that are not drained fast enough. Standing or slow moving runoff will cause water to enter your roof which will lead to a big expense on repairs later.

1.8 How to repair your roof
It all depends on the damage that needs to be repaired. the following are the most common repairs that need to be addressed on your roof. Of cause it will be best for it to be done by a professional, a person that’s trained and does this for a living.

– Zinc roofs (flat or standing)
In the case of zinc top roofs.

1)Rust

Rusted zinc sheets are the result of poor or no maintenance on your roof for a long time. Given time the zinc sheets will rust through and therefor fail in its task to keep the rain out.
Most times you will get away with removing the surface rust and apply a layer rust repellent before painting with a proper roof paint. However, this is a short term resolution because the rust will return in a couple of months.

It will serve you well if the zinc sheets are replaced altogether. Best to use the services of a professional. Not only will the task be done correctly but you will have the peace of mind that your belongings and family will stay dry and be protected against the weather.

2)Standing water

Water standing on your roof has the risk of moisture seeping in as well as dust accumulation which will promote rust and mold growth. This leads to the failure of your roof.
Get a specialist to inspect and repair the damaged area.

3)Lose fasteners

Fasteners, which holds the zinc sheeting tight to the beams, do come loos in time as a result of expansion and shrinkage as well as the wind tacking on the zinc sheets. This leads to openings where water will enter your roof and will cause the rotting of the wooden beams.

A professional will advise you best as to replacing the fasteners and properly sealing the potential water leaks.

4)Rotten beams

Even if these beams are properly treated, water and nature do attack them. Nature, in the form of insects, loves and has the ability to break down wood to be re-used by nature. Wood that is attacked like this weakens and will fail.

The replacement of damaged roof structure is advised. In order to get to the damaged area and replace it, all covering material needs to be removed. This is very labor intensive and you are advised to call in the specialists.

5)Missing fascia boards

The reason for facia boards is to protect the side of your roof. Just like fasteners on the top of your holding down zinc sheets, facia boards are held by screws or nails. These do come to lose over time. Fix the facia boards properly to your roof.

6)Cracked/damaged membrane

The UV light from the sun does break down the membranes over time (nothing lasts forever). You will typically find these membranes where the roof meets a side wall or a chimney.
Remove the damaged membranes and replace with fresh ones.

– Tile roofs
1)Broken/cracked or missing tiles

Tiles do damage from time to time. Inspect your roof regularly for those damaged tiles. Replace them as soon as possible.

2)Insufficient peaks and valleys

With insufficient nock and valleys there will insufficient flow of water. Then water can not be removed from a rooftop it will enter the roof and damage it. Mold will grow where there is moisture and that will lead to illnesses. Have your roof be inspected and corrected.

3)Cracked/damaged membrane

Membranes are placed where the roof tiles meet a wall or other structure on the roof like a chimney. These membranes should be replaced when found to be damaged.

– Concrete roofs
1)Standing water

Lookout for standing water on your concrete roof because it will lead to damage and mold growth. Damaged concrete will lend to the failure of the roof as well as mold growth with cost effects in the future. Have your roof’s runoff corrected and then sealed again.

2)Cracked concrete

Cracks happened when concrete expands and contracts during day and night time. When cracks are found they must be attended to as soon as possible. Have the cracks filled and then have the concrete sealed.

3)Cracked/damaged waterproofing

Rubber mats and asphalt does not last forever. Inspect the rubber mats and have them replaced if needed.

2 Waterproofing
2.1 Introduction
Waterproofing roofs are perhaps the most important factor when it comes to roof construction.

The National Building Regulations and Building Standards Act state that roofs must be designed and constructed safely so that they are not damaged by wind or any other natural force. The law also states that they must be waterproof, specifically:

-Roofs must be durable and must not allow the penetration of rainwater or any other surface water to its interior.

-Roofs must not allow the accumulation of any water on its surface.

But the legislation simply lays down the basics. For additional guidance, anyone building needs to refer to the South African National Standard that explains how the law can be successfully applied.

In terms of waterproofing, the Standard, The application of the National Building Regulations Part L-Roofs specifically covers:

-Roof coverings and waterproofing systems, and

-Drainage and waterproofing of flat roofs.

2.2 Roof Coverings and Waterproofing Systems
The SANS elaborates on the legislation stating that roofs must be able to resist the penetration of rain to the extent that water in category 1 buildings (see below) any water that penetrates the roof won’t run down the inside face of walls onto the floor or form damp patches on the ceiling or the floor. In terms of all other buildings (i.e. those that are not category

1), if water penetrates the roof it won’t be intense enough to run down the inside surface of the roof or drip onto the floor or ceiling.

The SANS also states those roof coverings and waterproofing systems must be capable of being repaired if damaged, even if the materials are old.
In addition, roof coverings must be able to resist:

-temperatures from -10 degrees C to +80 degrees C, as well as quick changes of temperature, without deteriorating

-the effect of UV radiation, without deterioration

-effects of condensation under the surface

-chemical attack from basic salt or gas in the atmosphere

-growth of bacteria, fungi, lichens and so on

-any penetration or puncturing while the roof is in use

-movement of the roof structure

All products that are used for roof coverings and waterproofing systems must have a lifespan of at least 10 years. If the structure or system is particularly intricate, making it difficult to replace, then the expectation is that materials used should have a lifespan of at least 20 years.

2.3 Drainage and Waterproofing of Flat Roofs
Flat roofs can be extremely difficult to waterproof, which is why all so-called “flat” roofs should be built with a fall of 1:80. This might require a steeper design slope of 1:50 in concrete slabs where construction is not always 100% accurate. A 1:50 slope is also required where there is an interruption in the flow of water on the roof.

The slope should be towards external gutters, roof edges and outlets. Other factors that should be considered include:

-an avoidance of “penetrations” through the roof or they should be at least 200 mm away from vertical surfaces like walls and “upstand” beams

-avoidance of having clusters of plumbing pipes, air conditioning pipes, and electrical conduit

-formation of a suitable step between inside and outside areas to prevent water flowing or dripping into the interior of the house or other building

It is very important that precast panels and precast roof structures are designed in a way that if there is the subsequent movement of the concrete elements, this will not damage the waterproofing system or compromise its performance.

The SANS has a really useful drawing that shows how construction drawings should clearly designate ridges and valleys and indicate the relative fall – or slope.

2.4 Flat Concrete Roofs
Any concrete roof design should take the thermal properties of concrete into account. This will be determined by a concrete technologist or another competent person, who will determine the required thickness of the concrete and its density, and design the roof in such a way that a waterproofing layer is built up.

Often the designer will incorporate a “thermally insulating layer” above the structural concrete deck. When this is done it is important that attention is given to ventilation so that any moist air that might accumulate below the waterproofing layer is vented to the outside.

The concrete used for flat roofs shouldn’t contain more than 7% moisture by weight, and sand-cement or lightweight screeds shouldn’t contain more than 10% moisture by weight.
If expansion joints to accommodate the flow of water are not custom-designed by a competent person, “twin kern upstand-type joints” should be installed over any expansion joints. These should be positioned away from any outlets and should be built in accordance with the illustration given in SANS 10400-L.

Upstand beams that are at least 170 mm high should be incorporated where masonry walls meet the concrete surface of the roof. At these “intersections” (i.e. where they join) corner fillets measuring at least 75 mm (vertically and horizontally) should be built-in. There is another drawing in the SANS that shows how this should be done. Another drawing shows how drips should be incorporated under all overhangs of concrete roofs.

In addition to these design elements, all concrete and screened roof surfaces must be waterproofed and constructed to the correct falls and cross falls (see the first paragraph under Drainage and Waterproofing of Flat Roofs above and the relevant section in the SANS). It is vital that there are no undulations in the concrete surface, and nothing should be allowed to protrude into the concrete or contaminate it.

The recommended finish for concrete roofs is wood floating. While the final surface should be sound and smooth, concrete and screened surfaces should not be highly polished. So they should NOT be power floated.

2.5 Waterproofing Systems
Any waterproofing system that is installed on flat roofs MUST be done by a “competent person” who MUST follow the manufacturer’s instructions. SANS 10400-L states that for roofs to be up to standard, they must remain watertight for at least five years without the need for any form of maintenance other than the normal cleaning of down pipes, gutters and so on.

It is also important that the person doing the installation is satisfied that the materials used are appropriate for that particular application, and should, therefore, take into account:

-the degree of exposure the waterproofing system will be subjected to

-how much protection the waterproofing material will have

-and ultimately whatever affects the building because of where it is located

It is important to realize that waterproofing systems can de-laminate if the substrates don’t allow any moisture vapor that has been trapped to escape. Generally, a sand-cement screed that is not very dense will allow retained moisture vapor to dissipate and therefore protect against the possibility of de-lamination.

SANS 10400-L suggests that a 20 mm screed is laid over all “lightweight” screeds because these are generally too friable and porous to provide good adhesion for waterproofing systems. The SANS also suggests that concrete and screened roof surfaces be allowed to dry thoroughly before any type of waterproofing system is applied.

Where waterproofing turnups are provided against brickwork and other masonry walls, they should be counter-flashed if they are not linked to the stepped damp-proof courses in cavity walls. The same membrane should be used, and the flashing should be cut into walls to a depth of at least 40 mm.

Generally, sand-cement coves with a radius of at least 45 mm should be formed at all the inside corners of both vertical and horizontal surfaces – unless a particular waterproofing system has a different design and doesn’t require this. Where there is a timber deck, 38 mm timber fillets may be fixed at all the junctions of horizontal and vertical surfaces.

There is always a potential problem with outlets. The installer must, therefore, pay close attention to overflow pipes, flues and so on, and make sure that the waterproofing material used covers everything but the opening. Generally, waterproofing membranes around any pipework should be clamped with a hose clamp or something similar, before the flashing is applied over the pipe.

If outlets aren’t the “full-bore”, coned type, pipes should be flanged so that waterproofing can be done correctly. Elements such as water storage tanks and solar absorbents should never be allowed to penetrate the waterproof layer.

All external corners and edges to be waterproofed should be rounded, and the height of all DPCs should be at the same level as the waterproofing turnups.
In addition to this part of SANS 10400, SANS 10021 also provides some information and guidance about the waterproofing of roofs. Remember, it’s important to do it correctly!

2.6 Gutters and Down pipes
Gutters and down pipes are not mandatory. However, unless gutters are designed by a competent person, they may only be located on the “perimeter” of the building. They should also be designed to ensure that storm water doesn’t penetrate the inside of any building if they become blocked at any stage.

Rain chain

Rain chains are a popular alternative option to down pipes from gutters

Outlets must be set flush with the concrete. If there is timber decking they must be recessed so that there isn’t any water standing around the outlets. Any outlets should be at least 500 mm from upstand elements including parapet walls, and they should be at least one metre from any expansion joints.

Installation requirements of manufacturers and suppliers of rainwater goods absolutely must be adhered to.

3 Painting
3.1 Introduction (From Wikipedia)
Paint is any pigmented liquid, liquefiable, or mastic composition that, after application to a substrate in a thin layer, converts to a solid film. It is most commonly used to protect, color, or provide texture to objects. Paint can be made or purchased in many colors—and in many different types, such as watercolor or synthetic. Paint is typically stored, sold, and applied as a liquid, but most types dry into a solid. Most paints are either oil-based or water-based and each has distinct characteristics.

For one, it is illegal in most municipalities to discard oil-based paint down household drains or sewers. Solvents for clean up are also different for water-based paint than they are for oil-based paint.[1] Water-based paints and oil-based paints will cure differently based on the outside ambient temperature of the object being painted (such as a house.)

Usually, the object being painted must be over 10 °C (50 °F), although some manufacturers of external paints/primers claim they can be applied when temperatures are as low as 2 °C (35 °F)

3.2 Roof painting (From Wikipedia)
A roof coating is a monolithic, fully adhered, fluid applied roofing membrane. Many roof coatings are elastomeric, that is, they have elastic properties that allow them to stretch and return to their original shape without damage.

Typical roof coating dry film thickness vary from paint film thickness (plus or minus 0.075 mm (3 dry mils) to more than 1 mm (40 dry mils). This means a roof coating actually becomes the top layer of a composite roof membrane and underlying system.

As such, the roof coating is the topmost layer of protection for the membrane, receiving the impact of sunlight (both infrared and ultraviolet (UV), rain, hail and physical damage.

Roof Coatings should not be confused with deck coatings. Deck coatings are traffic bearing – designed for waterproofing areas where pedestrian (and in some cases vehicular) traffic is expected. Roof coatings will only waterproof the substrates but will not withstand any kind of ongoing use by people.

Different applications for different roofs. Zinc roof tile roof concrete roof.

3.3 Interior painting [LINK]
Interior paint is made to be scrubbed, resist staining, and allow cleaning.

The wide variety of interior paints can be bewildering — but they exist for a reason. The trick is to be knowledgeable about their respective uses and strengths. Because there are such differences between the many paints, it’s important to know about each kind.

Although interior paints are available for every possible surface, there is no such thing as an all-surface paint. The wrong paint can damage a surface and often not adhere well, so it’s crucial to know in advance what goes where and when. Fortunately, modern paint technology has taken a lot of the risk out of choosing the proper paint.

Formulas for so-called “latex paints” have been improved to withstand dirt, moisture, and daily wear and tear, so these paints are no longer reserved exclusively for low-traffic areas. They are as washable and durable as the old oil base paints, so you no longer have to think in terms of latex paints for walls and oil base enamels for woodwork, windows, and doors.

Still, an important factor in interior paint selection — aside from personal color preference — is gloss. Regardless of the type of coating you choose, the gloss of the one you buy will affect both its appearance and its durability. High-gloss paints are the most durable because they contain more resin than either semigloss or flat paints. Resin is an ingredient that hardens as the paint dries. The more resin, the harder the surface.

Consequently, for kitchens, bathrooms, utility rooms, doors, windows, and trim, high-gloss paints are ideal. Semigloss interior paints, with less resin and a reduced surface shine, are slightly less wear-resistant but still suitable for most woodwork.

Finally, flat paints are the coatings of choice for most interior walls and ceilings because they provide an attractive, low-glare finish for surfaces that take little abuse and require only infrequent washings.

3.4 Exterior painting [LINK]
Exterior paints are made to combat against fading and mildew.

Choosing exterior paints can be complicated because of the wide range of surfaces. These surfaces include clapboard and aluminium siding, wood shingles, tar shingles, cedar shakes, brick, concrete block, stucco, and, of course, old paint. On many older homes, you’ll find a combination of these surfaces. Fortunately, there is an exterior paint for every type of surface, and some paints are suitable for more than one surface.

Like interior paints, exterior paints are available in either water-thinned or solvent-thinned formulas and in three lustres: flat, semigloss, and gloss. There are, however, several characteristics that distinguish exterior paints from those used inside the house. For one thing, exterior paints are more expensive.

They also contain more resin (for moisture resistance and durability) and more pigment (for color).

You may want to choose your exterior paint based on what was used before. As with interior paints, latex works best over latex and alkyd works best over alkyd. If you can’t tell or are unsure about what type of paint is on the house, use alkyd-base paint.

Latex exterior paints are easier to apply, dry quickly, and can help minimize moisture problems because they “breathe.” Cleaning up is a matter of soap and water. These paints do not adhere as well to oil-base or alkyd-base paints or too poorly prepared surfaces, however.

Alkyds, on the other hand, are extremely durable, but they are more difficult to work with and they dry slowly. Also, solvents must be used with alkyds to clean brushes, rollers, paint trays, and drips.

One of the alkyd types of exterior paint may be especially appealing because of its regulated, self-cleaning property. It’s called “chalking,” and that’s exactly what it does. Over a period of years, the paint surface slowly oxidizes. Each rainfall washes off a minute quantity of the paint — along with dirt.

As a result of this shedding, the paint surface is constantly renewing itself. The price of this convenience used to be chalky residue on foundations and shrubs, but the newest formulas control the shedding so it doesn’t stain adjacent surfaces.

Chalking paint is not recommended for every house. In areas with little rainfall, for example, the powder tends to remain on the surface, dulling the paint. In wet regions, chalking paint may not be worth the extra expense because frequent rainfalls will keep the outside of the house clean no matter what kind of paint is used.

If you live in or near either of these climatic extremes, ask your paint dealer if the chalking type is suitable for your area.

Roofing Contractor
Tremco provides a complete maintenance solution for your home (except for electrical and plumbing works). This roof repair, waterproofing and the painting contractor have 30 years of experience in (a) roof repair, (b) waterproofing roofs and walls as well as (c) painting of roofs, interior- and exterior walls.