Roofing Cement - It's All In The Combine

Roofing Cement - It's All In The Combine

Why are some trendy build roofs suffering ridge loss in heavy winds while older adjacent roofs stand agency? Similarly, roofs built within the final 10 years are affected by more cracking of the roofing mortar. What can we learn from roofing practices of the past?

The most obvious difference between immediately's roofing mortar and that used up to now is the mix. Traditionally lime was added to the mortar. A traditional lime mortar mix comprised of 1 part lime to 2 components sand/aggregate mix. Horse hair was added to strengthen the ridge bedding.

Portland cement

The introduction of Portland cement has just about eradicated the usage of lime mortar in roofing situations. Its compressive strength and quicker curing time make it preferrred for roofing applications. Portland cement is a lot simpler to mix and with added Plasticizers easier to trowel.

Up to the mid nineties it was frequent practice to include four parts cement to 1 sand/aggregate. Current suggestions advise growing the cement to 3:1 to be able to strengthen the mortar and promote a secure bond.

The rise in cement proportions could be the reason modern roofing pointing is affected by cracking and poor bonding. Increased cement content material leads to a quicker curing time or hydration. The combination simply dries out too quickly.


you will need to make sure that the curing time is managed particularly during periods of warm weather. I take advantage of soaked Hessian draped over the roofing to sluggish the process down. Bungee cords are attached to the sides of the Hessian. The cords hook beneath the roofing tiles to maintain it secure and away from the pointing. The Hessian will also shield towards "wash outs" ought to the climate change. In warmer climate I constantly spray the Hessian to maintain it damp.

To promote an adequate bond it's necessary to stop an excessive amount of suction from the substrate. If the roofing tiles and ridge are too dry they may suck the moisture from the combination earlier than a enough bond is made. The place doable the ridge tiles must be primed. Soak them in a large tub for an hour or so and moist down the top course of roofing tiles. If this isn't possible a combination of one half PVA to three components water must be utilized to the bonding area. This may prevent the roofing tiles from drawing an excessive amount of moisture away from the mortar.

Pointing a roofing valley

If you have tried pointing a roofing valley on a hot day you'll know the problems associated with cement slumping. You come back to a beautifully pointed valley to find the mortar has slumped leaving a niche between tile and mortar. A drier roofing mix is often utilized in an try to alleviate the problem. This isn't advisable because the cement combine requires enough moisture for profitable hydration.

Take a tip from "back within the day" and reinforce the mix. You should use stainless steel products used within the plastering industry. This strengthens the valley and stops the mix slumping. I lay a tentang semen indonesia size of L formed stainless corner bead every side of the roofing valley. It is fitted just behind the face of the valley away from roofing batons and underneath the roofing tiles. Don't hole the valley together with your fixing.