Pointing 110 yr old terrace

[firsthome10]

Hi, i recently bought my first home.

I have scaffold going up on monday for a new slateroof to be fitted andwant to utilise this and re-point my brickwork at the same time.

I work as a labourer for a local builder, who advised me to use a 5:1 sand/cement mix with plasticiser (we are getting a frost at night now in north england)

I just finnished repairing the chimney crown with this mix as the pointing.

However, i have been reading online about tips on doing the job since i dont quite trust the builder i work for and want to be sure before doing the main brickwork.

So,

Should i be using lime in the mix or is 5:1 sand/cement fine for a 110 yr old brick cavity house?

If i should be using lime should i remove the pointing from the chimney that i have just done?

I want to get on top of this before the roof is fitted to prevent disturbing the new slate.

thanks for reading

 

[firsthome10]

I should clarify that the brick is solid and appears to be glazed face brick and the cavities have vent bricks.

I am unsure whether it was built with lime mortar or cement.

The 'mortar' is light in colour and quite tough, except on the chimney stack where it is dried and powdery. The existing pointing is hard and ganular, it is cracking out of the joints in places.

Most houses in the street have been repointed in cement.

I point this out since i read it all depends on whether my house is built with lime already, and whether it needs to breath by default of its design.

 

[alittlerespect]

Hi

I would be surprised if you had cavity walls in a building that is 110 years old!

One point if I were you I would leave the external of the building alone until the spring - as you will possibly have noted we are now hitting the coldest part of the year and frost damage to the new pointing is likely to be your biggest headache. Also, you need to be aware that the original mortar would have been lime based which is more porous than cement and allows the joints to breathe whereas cement entraps the moisture and will encourage frost damage and the saturation of the brickwork which will lead to the walls becoming a lot colder in winter months.

The original pointing would most likely have been dressed up which would have provided a tough skin when hardened and over the last 110 years the mortar has been subjected to freeze/thaw cycles which will have led to the conditions that you are experiencing with the pointing.

When it comes to the repointing you should ensure that you rake out the original mortar joints, ideally 25mm or 1" in old currency - so as to resist frost damage! Lime mortar mix should be around 1 part Lime to 1 part Portland Cement to 3 parts Sand - others may have alternative suggestions!

The best of luck with your new venture!

Regards

 

[theoldun]

Firstly. The work that you have done on your stack will be okay. A lime mix is not required on a stack. unless it is very badly spalled. For pointing to a stack we use a 1 to 4 mix with a splash of admix or possibly 1-1-5, cement, hydrated lime, sand. For flaunching round pots we use 1 dust 2 sharp and 2 soft, how ever if you have flaunched with 1 to 5 soft you will be okay.
Regards your brickwork. You state house is 110 years old and cavity wall. Cavity walls did not come into being until approx 1925 to 1930 when builders realized it was 25 to 30 % cheaper to build cavity walling instead of one brick.
Next you state the cavity has vent bricks. Cavity walling does not have vent bricks. Where are these so called vent bricks and how many?
Next laying binder. Cement did not come into general use until approx 1930, so your laying binder will be either lime putty and sand with a pozzlana mix or a hydraulic lime sand mix, possibly the latter.
Pointing. From your description of pointing and the glaze on brick, it sounds that it was a rake and point job when built. With out seeing the structure we can not really tell. Couple more questions. Have you got any spalled bricks on main structure? Where pointing has blown and you can pick it out, does the texture on back of pointing look the same as the face of laying binder?
Answer the couple of questions and we will be only to pleased to try and help you out.
oldun

 

[firsthome10]

Thanks for the reply.

I was hoping i may be able to work in the small window of warmth we have (10am-2:30pm) as i will not be able to afford scaffold again next summer. If i cant get it done while im getting the new roof my only option is by ladder. Do you think this will be ok? Or would an additive make it possible?

I will take your advice and go for a lime based mortar. You have confirmed the many pages i have been trawling through on the web.

I must say however that i am surprised by the number of houses that have cement pointing, and how the guy that i work for today said, and i quote "limes ok to use if you want a lighter colour, other than that go no stronger than 3.5 :1" already differing from the prior recomendation of 5:1,,,

On a side note,

I may be out on the date of the house by 5yrs or so, i remember looking at the deeds before they went to the family solicitor and the house was built between 1900-1910, 1904 if i remember correctly.

I can confirm that it does indeed have cavity walls (on top of having very thick walls i watched next door have their cavities filled by the council this week) and can see the 'filled holes' where mine has had it done in the past.

 

[stuart45]

It depends on where you live as regards the start of cavity walls. In Portsmouth for example they were being built from around 1860.