The processes involved in roof restorations will vary according to the type of roof you have. The following information is the general restoration process for metal, tile or concrete roofs. Thanks to guys at Roof Restoration Brisbane for this article.
On the tiled roofs, any cracked or broken tiles will be replaced, while on metal roofs, sheet replacements or re-screwing have to be conducted first. Other repairs that include repairs or replacements to the flashings which will apply to metal and tiled roofs have to be completed before moving on to the other steps involved in a restoration.
The roof then undergoes a pressure cleaning using a minimum of a 3000 psi (pound per square inch) pressure. The typical domestic brands of pressure cleaners will usually only be able to produce about 1/3 of this pressure which is why the industrial water blasters are a necessity.
The power that the water blaster is able to produce is very important for any type of roof. However, it is particularly important for a tiled roof as any tiles that are more than 10 years of age usually do not have any glazing left. Once this glazing has eroded over time the underneath coating is exposed and starts to oxidize which results in a chalky substance. This needs to be removed as well as the build-up of grit and grime found on the surface.
In addition, special care should be used for the tile nose which is the end part of the tiles when cleaning. This is an area whereby many home-owners fail to clean their roof tiles correctly. If you look at a poor roof restoration you will probably notice that the end part of the tiles appear black. This is solely due to the fact that they were not cleaned correctly.
An inexperienced cleaner may want to avoid cleaning this area of the tiles as they are fearful that they may flood the cavity in the ceiling. It is very possible to push water underneath the tiles which will land up in the roof if done incorrectly. In order to avoid this issue, the lance should be held at a 60 degree angle and the cleaner will need to move quickly in order to stop the risks of having an excess of water build up in one area.
Re-Bedding And Pointing
If you have a roof that is tiled it will in most cases require re-pointing and in some cases re-bedding. If the roof requires re-bedding, this is a necessity when your ridge-caps have become loose and will involve the removal of the existing ridge caps followed by laying of concrete bed. If you are conducting your own roof restoration it is advisable to hire a bedding rail that you can rent from a few of the roof tiling supply yards in order to achieve a straight and neat bed. To make the concrete, combine cement and sand with 4 parts sand to 1 part cement. Make sure you also mix in a plasticizer into this mixture which will help the bed to maintain its shape. New ridge caps will then be laid onto the cement bed.
Wait at least 24 hours for the cement bed to dry before you apply your pointing. Use a flexible polymer-based pointing mortar as the flexibility is of great importance as roofs are typically subjected to movement so you need the type of mortar that is able to stand up to these movements. Your pointing will be applied using a pointing-trowel using between a 3mm and a 5mm thickness. If you decide to go thicker, the mortar will not be able to dry out underneath the mortar-skin and your pointing will start to sag.
In the majority of cases, when your ridge caps have not become loose a re-bedding is not a necessity. If this was the case, then you could skip the re-bedding process and just apply your pointing on the top of the current pointing.
The following part of a roof restoration is to apply a sealer or primer. Make sure you wait a day so that the pointing has dried out before you apply the sealer or the primer. If you have a tiled-roof you should be using a concrete sealer or primer, and when your roof is metal you should be using a “Gal” primer.
To conduct this task use an “airless” paint-machine that features a 5/19 tip. The primer should be applied according to the suggested coverage rates. These rates will be dependent on if the roof has been pre-painted or not. If the roof is not pre-painted you will require around 15 liters for every 100m2 on tiled roofs or around 10 liters for every 100m2 on the metal roofs. If you have a pre-painted roof you will need more primer and the amount needed will rely on how thick the first coating was if you were unable to remove it. When the coating is thick and the edges are more pronounced be prepared to use at least 50% more primer.
If you have a tiled roof and the surface if rough or bare you should be using filler coats to smooth the surface and build-it up. This offers a far nicer finish as well as prevents the patchy appearance you will often see when it comes to re-coating bare and old roof tiles. Like the sealer or the primer it is best to apply the filler coat with the airless paint-machine. The only difference is to use a bigger tip of around 5/21.
Again use the airless paint-machine using a 5/19 tip, apply at least 2 top coats by using a gutter to the ridge pattern using full strokes to the top and then back down. This will stop join markings from occurring in this coating and this technique is extremely important for the metal roofs which typically show up these join markings more.
When applying the top coat to the tile-noses point the gun in an upward direction as they require a thicker coverage as they feature craters and roughness. Some experts prefer to spray the bottom row of the noses first by going all around the roof opposed to going the usual up-and-down route. Whichever method you prefer when it comes to the tiled roofs you need to ensure the coat is thick enough to achieve full coverage on your tile-noses.
The coverage that you should be aiming for will depend on how porous and rough the tiles are. On average the majority of the roof coatings are able to cover around 1 liter for every 5 meters for each coat. If you have already used this rate to cover the roof and it still appears that it will need additional coating, it is highly advisable to use another coat. If your roof is extremely bare or rough you should ensure you purchase enough paint to allow for at least 3 coats. Alternatively you can use one filler coat as your 1st coat followed by 2 top coats.
Hand Painting And Cutting In
The majority of the typical roofs will feature a few parts that you won’t be able to spray. Some of these examples would be the Dutch Gabes or the lead flashings that go into the walls. These are the types of parts which you will have to hand paint.
The Drying Times
You should always check on the manufacturers recommendations in association to the drying times of specific paints. Make sure you have followed these suggestions as it can have an effect on your warranty. As a general guide when the temperature is over 20 degrees the roof coatings that are water based are usually dry enough for a second coat after an hour. If the temperature is between 15 to 20 degrees you should wait at least 3 hours between the coats. If the temperature is between 10 and 15 degrees expect to wait around 4 hours and if the temperature has fallen below 10 degrees it is highly advisable to wait for the next day before you apply the next coat.
Your walls, sky lights, finials and Dutch gables along with any other types of items on and around the roof needs to be covered or masked up. The plastic or masking tape can be purchased from a paint shop or hardware store. Avoid spraying on a windy day, a slight breeze is okay but high winds are a no go.