Bricks, Masonry, Asphalt and Concrete - Metal lathe over Hardibacker for interior veneer stone work?

I am going to be putting up some 1 inch veneer stone up to the ceiling over our gas fireplace in the new addition. I bought 1/2" Hardibacker, Type S mortar, sand, Acryl 60, and also have some diamand metal lathe that I had purchased when I thought I might use plywood as a backer instead.

Question is since I have the lathe already, should I also put it over the Hardibacker and cover it first with the scratch coat? Or should I instead just stick the first scratch coat directly to the Hardibacker and skip the lathe.

Here is the manufacturer's instructions for the veneer stone if it helps at all?

http://www.luckstone.com/arch/products/datasheet.php?sl_ID=148&CategoryId=17#Installation

What would be the advantage of the lathing, other than you already have it?

What would be the advantage of the lathing, other than you already have it?

I don't know. This is my first venture into masonry and I just want to make sure that the scratch coat is going to stick well to Hardibacker and not fall apart.

Basically I need someone to chime in and confirm that everything will be solid without the lathe or that things will be even stronger with it.

You do not need the lath. I would use an additive bonding agent in the type S mortar, mix it a tad dry and lay the stone from the top, though. Is it drystack or jointed stone?

You do not need the lath. I would use an additive bonding agent in the type S mortar, mix it a tad dry and lay the stone from the top, though. Is it drystack or jointed stone?

Remember I am new here, but if I understand you correctly drystack is gaps between and jointed is mortar fillinf the joints.

If that is the correct understanding than I was thinking that they would initially be layed drystack style and then I could go back later and fill the joints. to about 1/2" below the surface depth.

Hoe does that sound? Would you instead recommend that I form the joints as I go along with the lay?

Drystack means no visible joints. If it is a jointed style stone, then it is a little more tedious, and you have to exercise more care about slop.

Drystack means no visible joints. If it is a jointed style stone, then it is a little more tedious, and you have to exercise more care about slop.

Is this just a personal preference or is one way better?

Its a personal preference, it depends on the stones you buy whether they are jointed or not. look at the catolog and they will show you how to lay the stones.
Frank

Tuba_Transport -

You should also use a Type N mortar, as recommended by most stone manufacturers. Types M and S have too much portland cement.

The ASTM standards recommend using the mortar with the LOWEST compressive strength possible to carry the load. You really have no load to speak of. The reason is that the lower strength mortars have othe desireable properties that are more important than the compressive strength (workability, shrinkage, etc.)

Type S could work, but why buck hundreds of years of history and performance.

Dick

the easiest way to install this stone on an interior surface is to use tile adhesive, buy it in a pail and it saves you from using the wire lath and picking the right mortar and adding a bonding agent, its also a lettle cleaner then using mortar i have done probley 50 fireplaces with this stone jointed and stacked and never had a problem. you trowel the adhesive on with a v notched trowel you can do the whole surface at once if you want and wait a couple of minutes and then start from the top down, this will prevent you from having a cut at the top. If you have a mantel in the fireplace make sure its installed because if you install it after then you will either have to caulk where it buts up against the stone or you will have to cut it to fit around the grooves of the stone. the only load this stone carries is its own individual weight of each stone each stone is like hanging a picture . the load bearing element of this wall is the wall in behind it so make sure she's screwed down good.

Tuba_Transport -

You should also use a Type N mortar, as recommended by most stone manufacturers. Types M and S have too much portland cement.

The ASTM standards recommend using the mortar with the LOWEST compressive strength possible to carry the load. You really have no load to speak of. The reason is that the lower strength mortars have othe desireable properties that are more important than the compressive strength (workability, shrinkage, etc.)

Type S could work, but why buck hundreds of years of history and performance.

Dick

the manufacturer says to use 1 part Type S mixed with 2 parts sand. this prabably ends up being Type N but with a lower lime concentration I would guess.

thanks for the advice all. keep the opinions coming. i need it!

Type S is different from Type N, By varying the sand you get a stronger or weaker mix. Type N is stickier.
"MaSoNy mOrtar" is the way to remember the strenghts.
Frank

Technically, most masonry cements Type S and N are exactly the same, and neither contain hydrated lime. That is, they come from the same silo and are put into differently marked bags. If you read the weight of the bags, you will see that a bag of type N weighs 70# and a bag of type S weighs 75#s. There are type S bagged mortars available as well, and those contain portland cement and lime.

Confusion of portland cement, masonry cement and mortar cement is a very common problem for those not deeply involved in masonry. There are differences - that is the rason they are different matials and not just a different amount of sand.

Technically, the untimate mortar proportioms of Type N and Type S defined by proportions are different. A Type N contains a larger amount of lime in proportion to Portland cement. This gives the mortar more workability. The extra lime slightly reduces the COMPRESSIVE strength, but also provides some very beneficial properties like workability, bond and ability to heal (continue curing) over a long period of time. If you want the highest compressive strength, use Type M mortar.

If you want to learn about mortar look at the ASTM specifications for mortar. The commentary and appendizes we wrote are very valuable to explain the product.

If the stone manufacturer says "use Type S", then use Type S. Mortar types are selected to be compatible with the masonry units. - That is the reason there are different mortars, properties and proportions.

Dick

A lot of the confusion is because of the designation itself. "Type S" is a strength definition and can be achieved by using various components: Portland cement and Hydrated Lime or Masonry cement (which contains no lime). "Type S" masonry cement is a product that if mixed correctly, will produce a mortar of the strength designated by the "type S" classification.

Not to belabor the point, but a type of mortar (Types M, S, N, etc.) are types of mortar that are defined by either proportions or properties (but not by both). Certain materials require certain properties OR proportions.

The true, pure mortar is defined by proportions of portland cement and lime. To this amount of material, the proper amount of sand is added. Then, water is added to get the proper consistancy (not to be confused with workability).

Strength is on property of mortar, but is not usually the most important. The guys that fix things with a bigger hammer gravitate to a higher strength because it seems the easiest and simplest.

Mortars made using masonry cements and mortar cements are a simplied method of producing a mortar, but they must meet the designations of ASTM for properties after they are mixed. They do not have to meet the proportioning specifications, so they can be made from any number of materials added to cement. There is a long history of these type of mortars not being accepted as equals to the traditional portland cement and lime mortars from a standpoint of allowable stresses and inspection requirements.

If all you worry about is strength, then any mortar will be adequate. If you have other concerns like workability, bond, water-tightness, long term durability then you should used the correct type of mortar.

If a product manufacturer says to use a certain type of mortar with his product, use it!.

Dick

That is exactly the problem, ConcreteMasonry. In the lab it is strength, while on the job site it is proportional. The issue always arises when job site samples are subjected to lab standards. The problem is that many masons (because of improper field sampling/lab testing) use the lab strength as the basis for their field proportions and end up with a mortar that will perform poorly. It is STRONG, though, by damn!