The Brew Cabin

I posted a few weeks ago asking for advice on installing UFH under indian sanstone flags.

I am glad to report that the flags are now down, and the 190m UFH cable (ebeco) is in place! After some over complex calculations before we started we finished within 9 inches of the end of the room, not bad really, as the cable cannot be shortened!

Anyway, I have not tested the system yet, so it is a nervous time, and before I can I have to point the flags.

I have read the various posts regarding pointing, but I need some really basic tips as all this is new, and I do not want to spoil what so far has been a rewarding experience.

So here goes.

1. I was planning on using a 3.1 mix for the pointing. Is this correct?

2. The sand I have is quite gritty, will this be OK?

3. Do I need to add Feb to the mix?

4. How do I stop from staining the flags with the mortar?

5. If I do drop mortar on the flags am I best waiting for it to dry and brush off, or use a wet sponge to attack it straight away?

6. Any other tips I need?

Your advice last time was very useful, and was put into practice. As promised I have take loads of photos and will be sure to post upon completion!

Thanks in anticipation,

Mark

Hi Mark,

taking your Qs one at a time....

3.1 mix for the pointing. Is this correct?
A 4:1 mix will be fine - see the page on Mortars for guidance on a Class II mortar.

The sand I have is quite gritty, will this be OK
A building sand would be better, particularly for internal floors and for narrow joints.

Do I need to add Feb to the mix?
Any plasticiser will improve workability. At a push, a very small squirt of wash-up liquid added to the guaging water will do as a stand-in.

How do I stop from staining the flags with the mortar?
By being exceptionally careful, keeping the mortar just damp, not too sloppy and/or by masking the edges with tapem, cardboard or summat like that. With practice, a tradesman will be able to point flags by feeding in the mortar from a brick trowel, as shown on the Pointing page, and leave no marks on the flags, but, as I said, it does take practice and paitience - see Mike's Massive thread in The Craic

If I do drop mortar on the flags am I best waiting for it to dry and brush off, or use a wet sponge to attack it straight away?
I'd use a barely damp sponge immediately, and brush towards the joint, not across the flag itself.

Any other tips I need?
Take your time. Keep the mortar as stiff as possible. Don't overdo the cement - it doesn't bring any benefits to internal pointing. If you're really worried about your proficiency, consider using something like Geo-Fix.

Good luck! :)