Building a Masonry Firebox with Refractory Mortar Holland MI

Many fireplace masons in Holland are not familiar with refractory mortar, or they confuse the product with fireclay mortar. Masonry fireboxes are often laid in ordinary portland cement mortar, sometimes with a little extra cement or some fireclay added to make the mixture 'fireclay mortar'.

Master Chimney
(810) 424-4002
601 S Saginaw St
Flint, MI
 
Able Concrete Inc
(517) 371-4855
1305 S Cedar St Ste 105
Lansing, MI
 
Tip-Top Chimney Sweep
(810) 234-5000
3714 W Court St
Flint, MI
 
Northeast Solite Corp
(810) 232-3088
1071 E Grand Blvd
Flint, MI
 
Alpha & Omega
(517) 349-8660
3654 Okemos Rd
Lansing, MI
 
Brother'S Construction
(734) 665-8109
1235 Astor Ave
Ann Arbor, MI
 
Builder Mike
(586) 446-4640
11193 E 13 Mile Rd
Warren, MI
 
Giannola Masonry Co
(586) 792-2070
35086 Cordelia St
Clinton Township, MI
 
Hanneman & Fineis Concrete Construction Inc
(517) 371-4053
16101 S US Highway 27 Ste 6
Lansing, MI
 
Draper Group
(616) 304-9332
124 Fulton St E
Grand Rapids, MI
 

Building a Masonry Firebox with Refractory Mortar

Provided By:

Source: MASONRY CONSTRUCTION MAGAZINE
Publication date: October 1, 2006

By Bob Rucker

Many fireplace masons are not familiar with refractory mortar, or they confuse the product with fireclay mortar. Masonry fireboxes are often laid in ordinary portland cement mortar, sometimes with a little extra cement or some fireclay added to make the mixture “fireclay mortar.”

This approach is not surprising since the major building codes have been unclear, inconsistent, or silent on the subject. The ICC codes – recently adopted in many states –require refractory mortar for the construction of fireboxes, smoke chambers, and flue linings, but a short while ago only the NFPA 211 code called for “refractory mortar (ASTM C199, medium duty).” The BOCA code required “medium-duty fireclay mortar,” the UBC just required that the “joints in firebrick shall not exceed ¼ in.,” and the CABO One and Two Family Dwelling Code did not specify the type of mortar or size of joint to be used.

The problem with using ordinary mortar is that portland cement can't take the heat. Oddly, portland cement retains its strength up to fairly high temperatures, but deteriorates as it cools down through about 600° F. Eventually all that is left of the mortar is the sand and fireclay, with no cement binder. The mortar has no strength and easily falls out of the joints, especially if they are wide.

Refractory mortar, on the other...

Click here to read full article from Masonry Construction