Blasting advice

[Pford75]

I'd welcome some forum input on the subject of blasting.

We have a large building of mostly brick construction (but with one corner in flint where a previous building stood prior to ours being built in 1780).

Unfortunately, the previous owners covered the entire house in Sandtex which is obviously not good for the building and also never had LBC.

Given the size of the property, chemical stripping proved far too expensive, so we have had a few small test sections blasted by a reputable local company who work with E.Heritage and recently were involved in cleaning Blickling Hall nr. Norwich. They tried various substances (calcium carbonate being the softest and most expensive). There was no damage to the facings of the bricks (except 1-2 which are already blown and simply hidden by the Sandtex) or to the flints. It does look as though repointing will be necessary though.

Anyone have experience of blasting? What to look out for etc.?

Finally, would you imagine the CO will request a formal LBC application or is this likely to be a 'no consent required' job? LBC application will push me out apx 10 weeks in my area and therefore too late in the year for repointing with lime....I'd really like to get the work done ASAP, hence prefer 'no consent required'.

Thoughts?

 

[NT]

The vortex thingy is he usual answer for these situations. Bulk chemical stripper is very cheap if you use caustic soda.


NT

 

[Pford75]

What is the cortex thingy?

The cost of chemical stripping wasn't the materials, but the labour....I work full time and the cost of having someone strip it (chemically) for me was too high

 

[Gareth Hughes]

I'd welcome some forum input on the subject of blasting.

We have a large building of mostly brick construction (but with one corner in flint where a previous building stood prior to ours being built in 1780).

Unfortunately, the previous owners covered the entire house in Sandtex which is obviously not good for the building and also never had LBC.

Given the size of the property, chemical stripping proved far too expensive, so we have had a few small test sections blasted by a reputable local company who work with E.Heritage and recently were involved in cleaning Blickling Hall nr. Norwich. They tried various substances (calcium carbonate being the softest and most expensive). There was no damage to the facings of the bricks (except 1-2 which are already blown and simply hidden by the Sandtex) or to the flints. It does look as though repointing will be necessary though.

Anyone have experience of blasting? What to look out for etc.?

Finally, would you imagine the CO will request a formal LBC application or is this likely to be a 'no consent required' job? LBC application will push me out apx 10 weeks in my area and therefore too late in the year for repointing with lime....I'd really like to get the work done ASAP, hence prefer 'no consent required'.

Thoughts?

Given that I have a horrid feeling I (or one other fairly regular poster here) might actually be your CO, then I have to say yes, consent probably is required :twisted:
Sorry, but otherwise every other Tom Dick and Harry (with less honourable motives) would start stripping and repointing (in lovely thick snail-track cement)
Give your CO a ring though, he or she might be able to come to an arrangement.

 

[Nemesis]

I thought maybe you were the CO - and certainly you are the CO where Blickling is concerned? Maybe you have a view on why that was done by the NT? ? I find it rather surprising. Only time will tell really if it was damaging or not.

The 'other' is away until Monday BTW.

I would urge major caution where blasting is concerned. It can cause long term damage. And certainly I would think that it would require LBC as removal of paint and also something which has the potential to damage would require the input of the CO?

Where repointing is concerned - this too would surely be best to have the CO's input? It can hugely alter the appearance of a building and requires careful thought. Not something to rush.

http://www.spab.org.uk/publications_Q&A_brickwork.html

http://www.midsuffolk.gov.uk/Environment/Buildings/traditionaldetails/Brickwork.htm

 

[Pford75]

Thanks for the advice - certainly I will be speaking with the CO....I was just hoping to get the work started otherwise, it will be too late in the year for lime repointing.

Given that the original coat of Sandtex never had LBC.....would you envisage any problems in obtaining LBC for it's removal?

 

[Nemesis]

Maybe that may depend on what is proposed in the way of removal, and the advice of the CO in the matter of suitable pointing after.

Making a bad situation worse isn't always what conservation is about!

In this case obviously you aim to do the right things, but talking first to the CO is the best route.

PS if it's Gareth I'd talk to him asap...

 

[Pford75]

No - it's not....and I've already placed the call

We've previously had LBC for works and I'd always seek a formal note of 'no consent required' before doing something like this anyway.

I guess another 6 months of Masonry Paint can't do that much harm anyway.

 

[Moo]

We were faced with exactly the same problem (years of Sandtex over soft red brick) and chickened out of the poultice solution because of the cost.

Looking back, I wish we'd simply spread the work over a number of years, just doing one face at a time as and when we could afford it..

p.s. we tried test patches of all sorts of mechanical removal but all of them took the face off the bricks; the only thing that was effective and undamaging was one of the poultices - but I can't remember which.

 

[Pford75]

Moo - thanks for the advice

Although our test patches indicate that the bricks are okay and there was no damage on the various sections we tested.

Did you find a lot of resulting mess after removal?
Can you share your mechanical removal costs with me - I'd love to have something to compare my quote to? Can do it offline if you'd rather not post on here...

 

[Penners]

I think the only advice on blasting that I can give is: avoid anyone whose previous job was in a quarry.

 

[Moo]

Pford - I'm afraid I can't share any information about mechanical removal costs, because in the end we just left it as it was, peeling Sandtex and all.

That was years ago, and we don't live there any more, but I still feel terribly guilty about it.

Regarding mess - we now live opposite a building that was cleaned with some sort of mildly abrasive water-born jet a couple of years ago (just to remove decades of traffic film). They were very careful, but all the cars parked in the street were covered with a fine film of creamy stuff. When we had the test patches done with the poultice (I'm pretty sure it was Strippers of Sudbury) they covered the ground with protective plastic which caught the run-off when they did the final rinsing. The paint came off in sheets, along with the poultice, so there wasn't any mess.

 

[Pford75]

Thanks - really helpful...I'll be waiting until the Spring now as will need repointing....

 

[Lime]

There was a listed property sandblasted several years ago near where I live.
it was done without permission and it ruined the brick.
It still stands out like a sore thumb particularly when compared to it's neighbours.
Now the brick looks grubby and dirty with no aging to enhance it.

 

[Moo]

Yes - that was the great thing about the poultice. The bricks looked exactly the same as I imagine they looked just before the first vandal painted them in the 1920s