Cold Weather Requirements for Masonry Construction

COLD WEATHER MASONRY CONSTRUCTION

BAC CONTRACTORS

IMI-TRAINED CRAFTWORKERS

International Union of Bricklayers and Allied Craftworkers

International Masonry Institute

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COPYRIGHTED MATERIALS

1. understand - code requirements for cold weather masonry construction

IBC 2012/MSJC 2011 IBC 2015/MSJC 2013

2. learn - Industry Guidelines and Common Practice 3. apply - appropriate actions for successful results 4. learn – helpful tips to plan for winter construction

LEARNING OBJECTIVES

COLD WEATHER MASONRY

CONSTRUCTION

SPECIFICATION FOR MASONRY STRUCTURES

PART 1 - GENERAL

1.5 - Submittals

1.5 B. Submit the following:

3. Construction procedures

a. Cold weather construction procedures

IBC & MSJC

BUILDING CODES

2015 IBC goes with 2013 MSJC

MSJC date will be one or two years prior to companion IBC

IBC supersedes MSJC at points of conflict

IBC: the legally adopted model code

MSJC: the referenced standard

2015 INTERNATIONAL BUILDING CODE

SECTION 2101 GENERAL

2101.2.6 Masonry Veneer

CHAPTER 21 - MASONRY

Masonry veneer shall comply

with the provisions of Chapter 14

or Chapter 6 of TMS 402/ACI

530/ASCE 5.

SECTION 2104 CONSTRUCTION

2104.1 Masonry Construction

Masonry construction shall

comply with the requirements of

Sections 2104.1.1 through

2104.4 and with TMS 402/ACI

530/ASCE 5.

CODE COMPARISONS

IBC ‘03 & ‘06 MSJC ‘02, ‘05, ’08,

’11, ‘13

PART 1 - GENERAL 1.8 – Project Conditions

1.8 C. Cold weather construction

Chapter 21: MASONRY Section 2104.3

Cold weather construction

but not ’09, ’12, ‘15

Beginning in 2009, IBC does NOT

have hot/cold weather provisions.

All are moved to the 2008 MSJC

CODE COMPARISONS

IBC 2104.3 (’06)

Cold Weather Construction ◦ The cold weather

construction provisions of ACI 530.1, (etc.) Article 1.8C OR the following procedures shall. . .when EITHER the ambient temp, OR the temp of masonry units is below 40o F.(4o C)

◦ Visible ice and snow shall be removed…

MSJC 1.8C (’08, ’11, ‘13)

Cold Weather Construction ◦ 1. Implement the following

requirements when: The ambient temperature falls

below 40oF (4.4oC) Do not lay units having either

a temp of 20oF (-6.7oC) or visible frozen

moisture

WHEN MUST COLD WEATHER PROVISION BE IMPLEMENTED?

WHY 40º ?

The temperature at which hydration of cement slows and eventually stops

Supported by research and decades of empirical evidence

Hydration is the ability of the cement to take on water and complete its chemical reaction. No hydration = no strength development

The chemical process of hydration produces heat

PERFORMANCE TARGETS

Keep the mortar between 40oF and 120oF

Don’t lay frozen units or allow the masonry to freeze before initial set

Protect the masonry from freezing after construction

Result: the masonry will perform as expected

SPECIFICALLY…

1. General Provisions

Apply to all types, all temperatures

2. Construction Provisions

Options available for how to meet targets based on job site conditions

3. Protection Provisions

Care for the masonry during and after construction

TEMPERATURE

Ambient Temperature: Current outdoor temperature at the time considered

Mean Daily Temperature: Average of the projected maximum and minimum daily temperature, midnight to midnight

Anticipated Daily Minimums: Lowest temperature forecast for the upcoming 24 hrs.

TEMPERATURE

Ambient temperature

Construction

Mean Daily Temperature

Protection, ungrouted masonry

Anticipated Daily Minimum

Protection, grouted masonry

TEMPERATURE

Mean Daily Temperature

Average of the projected

maximum and minimum daily

temperature, midnight to midnight

54º + 36º / 2 = 45º

Ambient Temperature

Current outdoor

temperature at the time

considered.

Anticipated Daily

Minimum

Lowest temp

forecast for the

upcoming 24 hrs.

considered for construction

considered for protection, ungrouted masonry

considered for protection, grouted masonry

TEMPERATURE Anticipated Daily Minimum

Lowest temp forecast for the

upcoming 24 hours

considered for protection, grouted masonry

GENERAL PROVISIONS

Keep units and other materials dry

Do not lay frozen units (units < 20o) or those with visible ice or snow

Do not overheat water or aggregates

It is not necessary to heat grout materials unless their temps are below 32o

protected not protected

Keep units and other materials dry

Do not lay frozen units or those with visible ice or snow

40o – 32o F

CONSTRUCTION PROVISIONS

Do not lay glass units below 40o

Heat sand OR water to achieve mortar temps of 40o – 120o at time of mixing

32o to 25o F


All of the above, plus:

Heat sand AND water to achieve mortar temps of 40o – 120o at time of mixing

Maintain materials above 32oF until used

Heat grout aggregate and water to keep grout above 70oF

25o to 20o F



Add windbreaks or enclosures when wind is above 15 mph

Make sure masonry is above 40o before grouting


20o F and below


Add auxiliary heat to enclosures

Keep enclosed area above 32o F


Heating water is the most effective technique because of its ability to retain heat and impart heat to other ingredients

Heated water used to mix mortar in the enclosure



Silos partially enclosed, heat provided

in mixing area

Mortar must be at least 40o at time of mixing


Metallic surface contact thermometer


PROTECTION REQUIREMENTS

What’s good for the masonry is also good for the mason.

Productivity and safety are improved with enclosures

IBC2104.7 Masonry

Protection

◦ The top of unfinished

masonry work shall

be covered to protect

the masonry from the

weather.

MSJC 1.8B Masonry

Protection

◦ Cover top of

unfinished masonry

work to protect it from

the weather.

Note: These provisions apply

regardless of temperature.


Barely adequate

Very good Overkill

COVER UNFINISHED WORK

IBC 2006: 2104.3.3- 2104.3.3.3.5 ◦ 6. Where mean daily

temperatures are between [all ranges down past 20oF(-7oC)], completed masonry shall be completely covered with a weather-resistant membrane for 24 hours after construction.

MSJC 2011 1.8C ◦ 7. When mean daily

temperature is between [all ranges down past 20oF (-6.7o C)], completely cover completed masonry with a weather-resistive membrane for 24 hr after construction.

Note: These are reference locations for those using

the 2006 IBC/2005 MSJC and prior. These are found

only in the MSJC from the 2005 edition forward.

PROTECTION, UNGROUTED MASONRY

Temperature Ranges for Protection Based on

“Mean daily” temperatures for ungrouted

masonry (forecast 24-hour average)

“Anticipated daily minimum” temperatures for

grouted masonry (forecast anticipated minimum)


40o – 32o F

◦Maintain glass unit masonry above 40o

for 48 hours

◦ Protect newly-laid masonry with weather-

resistant membrane for 24 hours


32o – 25o F

◦Repeats requirement

from prior temp range

– cover for 24 hours


◦ (no additional

requirements)

25o – 20o F

The above, plus

◦ For ungrouted masonry, cover

completely with insulating blankets, or

equal, for 24 hours

◦ Increase to 48 hours for grouted

masonry unless Type III cement only is

used in grout. (New in 2003 IBC)


Insulating blankets cover top of wall

INSULATING BLANKETS

20o F and below

◦ The above, plus:

◦Maintain new masonry above 32o for 24

hours with heated enclosures, lamps, etc.

◦ Increase to 48 hours for grouted masonry

unless Type III cement only is used in

grout.


Heated enclosure

PROTECTION OF MATERIALS

Enclosure on site made from scaffold framing and heavy plastic sheeting

300,000 BTU heater

Thermostat set to 50oF over the weekend

6 pallets of block and drum of water

Heated enclosure

Moving material into enclosure



Ambient temperature in enclosure keeps masonry units warm

Inside of enclosure


In cold weather, bricks

with IRA of 25-30 may be

desirable

5-25 g/min/30 in 2 Recommendation:

INITIAL RATE OF ABSORPTION

Using a high IRA brick

reduces the risk of

freezing by more rapidly

absorbing water from

the mortar or grout.

INITIAL RATE OF ABSORPTION

If a low IRA brick is

used, water content of

the mortar should be

the minimum necessary

for workability

© 2009 INTERNATIONAL MASONRY INSTITUTE

ELEVATIONS DIAGRAM 01.410.0311 REV. 08/10/09

MORTAR JOINT MATERIAL TAKEOFF

UTILITY BRICK, RUNNING BOND MODULAR BRICK, RUNNING BOND

4 @ 12” x 3/8” = 18.000 SQ. IN. BED JOINTS

HEAD JOINTS 8 @ 2.3125” x 3/8” = 6.938 SQ. IN.

2 @ 1.3125” x 3/8” = 0.984 SQ. IN.

25.922 SQ. IN. MORTAR

3 @ 12” x 3/8” = 13.500 SQ. IN.

3 @ 3.625” x 3/8” = 4.078 SQ. IN.

17.578 SQ. IN. MORTAR

18.00% MORTAR 12.21% MORTAR

ONE SQUARE FOOT ONE SQUARE FOOT

18% 12%

MORTAR

Cold weather retards the hydration of the cement in the mortar mix.

Mortar mixed in cold weather often has lower water content, increased air content, and reduced early strength.

Mortar with lower lime content will allow the water content to decrease more rapidly

Mortar with over 6% water content will experience disruptive expansive forces if frozen, due to the increase in volume of water when it converts to ice.

Avoid scorching the sand or overheating the water, which can lead to discolored mortar and flash setting.

Avoid wide variations in mortar temps, causing variations in tooling times and possible variations in mortar color.

MORTAR

Highly

magnified,

frozen mortar

has fissures

that can

reduce

compressive

strength and

inhibit bond

MORTAR

ADMIXTURES

Accelerators are admixtures used to speed the setting time of mortar and grout.

By increasing the rate of hydration, accelerators increase the rate of early strength gain.

Avoid calcium chloride: it causes corrosion to metal accessories and possibly efflorescence.

Safer: accelerators w/ inorganic nonchloride compounds like calcium nitrite and calcium nitrate.

Avoid antifreeze: it reduces compressive and bond strength of mortar.

EFFLORESCENCE

EFFLORESCENCE

MORTAR

Bond separation

Brick & mortar leak

Wall system must address moisture penetration

MOISTURE RESISTANCE

RECESSED COURSE

MOISTURE RESISTANCE

ARCHITECTURAL EFFECT DETAIL 01.601 REV. 08/31/07

BRIC

K &

BLO

CK C

AV

ITY W

ALL

MORTAR

WASH

DETAILING MASONRY

SERIES www.imiweb.org 800-IMI-0988


RECESSED COURSE

MOISTURE RESISTANCE

FULL HEAD JOINTS

MOISTURE RESISTANCE

PRODUCTION

If contractor figured job with pipe scaffold, (e.g. loadbearing) add 5-7% more for cold weather construction

If contractor figured job w/ hydromobile scaffold, add 15-20% for cold weather construction

If normal conditions call for 4 laborers for every 8 bricklayers, cold weather conditions call for 5 laborers

Production slows down, e.g. cut rebar into shorter pieces to work around enclosure

FACTORS AFFECTING RESULTS

Code provisions

+ Planning

+ Skilled Execution

= Successful cold weather masonry construction

FOR GOOD RESULTS

For best masonry performance in cold weather

conditions:

◦ Mason contractors: Plan ahead and submit a

plan, if required

◦ Be flexible, the weather is unpredictable

◦ Remember that top performance is the goal

and the code allows for the application of

reason and common sense.

FOR GOOD RESULTS

General Preparation and Construction Requirements: Store units and other materials in dry conditions off the ground. Do not lay frozen

units (those with temperatures below 20o F) or those with visible ice or snow. Do not heat water or aggregates above 140o F. It’s not

necessary to heat grout materials unless their temperatures are below 32o F.

TEMPERATURE

RANGES

CONSTRUCTION REQUIREMENTS

Ambient Temperatures

(During Construction)


Mean daily temps for un-grouted masonry, and

anticipated daily minimums for grouted masonry for

period following construction

40o F to 32o F Do not lay glass units.

Heat sand or water to achieve mortar

temps of 40o F to 120o F, at time of mixing.

Maintain glass unit masonry above 40o F for

48-hours.

Protect newly laid masonry with weather-resistant

membrane for 24-hours.

32o F to 25o F

Maintain materials above 32o F until used.

Heat grout aggregate & water.

Keep grout above 70o F.

No additional requirements beyond those above.

25o F to 20o F

Add windbreaks or enclosures when wind

exceeds 15 mph.

Heat masonry to 40o F prior to grouting.

Cover new masonry completely with insulating

blankets, or equal, for 24-hours.

Increase to 48-hours for grouted masonry unless

Type III cement only is used.

20o F and Below

Add auxiliary heat to enclosures.

Keep area above 32o F.

Maintain new masonry temps above 32o F for 24-

hours with heated enclosures, lamps, etc.

MSJC-13 COLD WEATHER REQUIREMENTS

IMI Tech Briefs,

Document 2.5.6

(Included in your

handouts)

BIA Technical Note #1

(www.bia.org)

NCMA Tek Note 3-1C

www.ncma.org)

NCMA Tek Note 1-2B

Portland Cement

Association (PCA)

(www.cement.org)

ADDITIONAL RESOURCES

BAC CONTRACTORS

IMI-TRAINED CRAFTWORKERS

International Union of Bricklayers and Allied Craftworkers


COLD WEATHER MASONRY CONSTRUCTION

Cold Weather Requirements for Masonry Construction

Education

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