Estimating Mortar Quantities

[Wrekin1]

Hi,

 

I'm looking for information on quantities of mortar I'll need for my costings. I have found what, to this newbie at least, looks a great table from the Mortar Industry Association website for bricks (http://www.mortar.org.uk/documents/info-housebuilders09.pdf) but cannot find anything as specific for blocks. I'll be using a mix of 300mm 140mm and 100mm wide blocks for the foundations and outer skin but other than a few generic references to 1m3 of mortar will do 800 100mm blocks and I should use a mortar/sand mix 1:3 below DPC and 1:6 with a Pasticer mix or 1:1:6 for an OPC/Lime mix above ground all from the HBB or various websites I'm struggling to find anything more detailed / specific.

 

If anyone has more advice or anything more detailed such as the link for the mortar for bricks it would be most gratefully received.

Thanks

[PeterW]

Try this

 

http://source4me.co.uk/calculate_brick_block_mortar.php

[Wrekin1]

Peter hi,

 

Thanks for this. I've some follow up questions.

 

The table appears to give a mix ratio of 1:3.5 or is this because I need to calculate the kg weights of the sand and mortar in the table to litres?

The amount of m3 required appears linear between the 100mm, 140mm and 215mm blocks per the table, Am I safe to extrapolate up to a 300mm block?

What if I want to change the mix to a 1:5?

 

I am probably being too detailed over something which in the grand scheme of costs isn't enormous but as I have to submit my costings to my lender I don't want them finding unnecessary holes in my calculations. Also just because of my background I struggle to accept calculations off a website without understanding them fully

 

Finally does anyone has advice on the correct mix above OPC for blocks for the outer skin above DPC? They will be rendered over so the colour of the mortar is not important.

 

Again many thanks.

 

 

[PeterW]

I've got to say I don't bother with mortar mixed on site these days as its a faff and mixers never get cleaned properly !

 

Local readymix place does mortar tubs that mean I get a full day out of a 1:1 gang and the labourer is loading up etc - also a consistent mix and no piles of sand etc to get full of crud and leaves. I think when I costed it we were on a par for price.

 

Edited to say it's about £48 per 1/3 cubic metre tub which will do 5-600 bricks or 400 blocks. 

Edited November 21, 2016 by PeterW

[Oz07]

If just submitting your costings to lender then definitely don't waste too much time on mortar!

 

like you say use online calc and multiply if you have a 300mm thick solid wall. Although usually 2 100mm leaves ie times 2

[PeterW]

@Wrekin1 I'm not sure where you get litres from either ...??

 

From the link, 150m2 of block work is 1500 blocks. In my calcs that is 4 tubs of ready mix at £192

 

To do the same on site mix is 36 OPC and 4 bulk sand, coming in at around £220 not including site mixing ....

[Wrekin1]

Thanks guys! Sometimes I can get too bogged down when I don't have the details and it's good to be reminded not to do so on something where the cost impact on the whole project is so small.

[PeterW]

Have you considered something like a service such as the one from Estimators Online ..?? They need to be "tweaked" some times as their system can be a little odd but it should give you and the lender a decent understanding of the real cost levers. 

 

Is the plan to build all 3 concurrently ..??

 

[Wrekin1]

Once I get my final costings I was planning to go to use a QS to give a sanity check for the lenders. They seem to want that type of reassurance but I'll check the service you suggest.

 

Yes the intention is to build concurrently at least up to timber frame or watertight but then to stagger the various fit stages in order to help the cash flow. It means a real stretch in the short term but the savings in ground works and placing one contract for the frame should be a longer term gain.

Edited November 22, 2016 by Wrekin1

[PeterW]

I would add some caution to that approach as you may miss things and also you have no baseline to challenge any costs. 

 

For example if your groundwork quotes all come in quoting based on concrete at £145/150/155/cuM, what have you got to baseline against if you don't have an independent view of the costs or quantities involved ..? Having a QS after the fact is potentially extending your timelines as  you may have to go back and challenge your supply chain. 

[Wrekin1]

Sorry Peter, I probably wasn't clear. I mean to go to the QS / estimating service after I have all my own estimates (I want to understand what the QS says) but before going out to tender from contractors.

[Wrekin1]

On 21/11/2016 at 19:24, PeterW said:

@Wrekin1 I'm not sure where you get litres from either ...??

 

From the link, 150m2 of block work is 1500 blocks. In my calcs that is 4 tubs of ready mix at £192

 

To do the same on site mix is 36 OPC and 4 bulk sand, coming in at around £220 not including site mixing ....

Peter, Just as a quick reply to your question on the litres, and in case someone else may be interested in the future, the litre reference came from the table in the link you sent me but also from the HBB Mortar mix chart (Table 2 - What's in a m3 of mortar - p 293 of the 11th edition) where, for example, for his OPC/Lime mix (1:1:6) he gives the following quantities:

 

Sand 1000 l, Cement 175 l, Lime 175 l.... with the equivalent weights of: Sand 1,600 kg, Cement 245kg, Lime 105kg.... thus the 1:1:6 ratio comes from the litres volume rather than the kg weight.

[PeterW]

Aaahhhh....!!!

 

OK I'm used to using a mix box : bucket so the ratios are 3 buckets sand, half lime, half OPC in a standard mixer. 

 

I've never actually thought of that in litres ..!