High Performance Exterior Masonry Wall Design and J.B. SPEED SCHOOL - - PowerPoint PPT Presentation
High Performance Exterior Masonry Wall Design and J.B. SPEED SCHOOL Detailing for Water OF ENGINEERING Resistance, Thermal Control and Crack Control W. Mark McGinley, Ph. D., PE FASTM MASONRY SEMINAR Masonry Institute of Iowa Thursday,
J.B. SPEED SCHOOL OF ENGINEERING
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MASONRY SEMINAR Masonry Institute of Iowa Thursday, March 2, 2017
The presentation will address the following learning objectives:
systems and discuss their behavior as it relates to their function as a building
vapor and thermal barriers.
moisture penetration, vapor transmission, etc
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control and detailing for differential movements.
and thermal mass effects on energy use in walls systems.
exterior masonry wall configurations and costs.
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Functions
moisture (and vapor)
so inherently
Must do so in a aesthetically pleasing, durable, cost effective manner
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Single wythes of masonry can leak Drainage Walls OTHER TYPE BARRIER WALL All Single wythe
To be effective moisture barrier must detail for Fault Tolerance at Critical Locations
Extend flashing on sill up behind window Make Cavity at least 2 in – Free to allow for tolerance and mortar fins- code – 1” Consider Extending flashing to shelf angle instead under sill brick – short heights – BIA.org - Positively Anchor Sill
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Show and detail end dams where needed
Step flashing down
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Stainless steel edge
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Detail and show how to attached flashing to backing system Extend flashing
brick staining If you don’t like drip edge look Alternative way to provide this Perma Barrier
more later
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For conductive Thermal movements -Do one of:
a)
Meet prescriptive R , U values in Energy code
b)
Do a detailed energy analysis (LEED) c) Comply with ASHREA 90.1 – Prescriptive & Detailed analysis See my earlier Talk
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ASHREA 90.1 Walls – (Not windows or doors) can be air barriers if they:
(a)Have materials that have an air permeance not exceeding 0.004 cfm/ft2 under a pressure differential of 0.3” w.g. (1.57psf) OR (b) Assemblies that have average air leakage not to exceed 0.04 cfm/ft2 under a pressure differential of 0.3” w.g. (1.57psf). OR (c) Building demonstrates air leakage rates of ≤ 0.40 cfm/ft2 at a pressure differential of 0.3” w.g. (1.57 psf) (2.0 L/s.m2 @ 75 Pa) Exception: Buildings in Zones 1, 2, and 3 constructed with mass walls are exempt.
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a)
Put vapor barrier on warm side of insulation when cooling degree days are greater than heating degree days and have a vapor permeable Air/moisture barrier.
b)
In mixed climates and some wall systems its hard to find warm side- Do not have two vapor retarders!
c)
Some times better to have no vapor
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Movements are produced by:
and any supporting structural systems
See BIA Tech Notes 18 and 18A and NCMA TEK Notes 10-1A , 10-2A, 10-3
Brick are the smallest when cooled from the kiln. Expansion ranges from 0.0002 to 0.0009 in/in Codes gives ke= 0.0003 in/in.
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Clay masonry can expand significantly Benson Conv. Sealant forced out
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The primary function of this joint is allow free expansion of the masonry but must also resists water penetration and air movement Note that expansion joints and control joints not the same
BIA Tech note 18A Vertical ExpansionJoints
Note that most sealants require a backer rod and the sealant depth should be about ½ the width of the joint (min ¼”) – Types include urethanes, silicones, polysulfides.
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A conservative estimate of vertical expansion joint spacing, Se, can be made using
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w = is the width of the joint (in) ej = the extensibility of the sealant (%) Tech note 18 and 18 A suggest equation above can be reduced to
j e
For Example: for a 50% sealant, 3/8” joint, and 3/8” joint with the simplified equation: Se = 17’-4” ½” joint would have a spacing of 23’- 2”
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Corners Place joints near corner
will develop BIATech Note 18A
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Corner opening cracks
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Not an expansion joint just caulk
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Be careful with support at corners
Backing wall
Must have at least two ties on each Leg of column cover
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Offsets This is sort of a corner and an offset movement Benton Cov.
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No expansion joint creates crack as shown (TMS) These are not due to settlement (up)
Sections with openings move less and provide restraint to upper portions
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Openings
There are
and below and a solid section between the edge column section is connected to both and creates distress due to differential movement 34
Openings
You should place a vertical expansion joint at
loose angle is used it must be allowed to expand independent of brick - note min 4” bearing length of angle Need to put on both sides if large opening or lintel supported on backing
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You should place a vertical expansion joint at changes in heights, thickness an types of walls and
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The parapet wall is exposed on three sides and usually moves more than other walls. Also a parapet has much less dead load restraint. The usual rule of thumb is reduce the spacing of vertical expansion joints in parapet to ½ elsewhere.
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Hidden joints can improve Aesthetics
Brick moves up Frame shortens
Horizontal expansion joints typically placed below shelf angles They should be sized for the masonry and frame movements Ensures Masonry Non loadbearing 39
Note that the total joint size must include the angle thickness and it will be very difficult to get a 3/8” thickness
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Can hide the joint with lipped brick – BUT THESE CAN CHIP BADLY
What’s wrong with this detail?
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Problems – Closed mortar joints - Harbor
Cracked away
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Problems – Closed mortar joints – Benton Conv
Placement of Horizontal Expansion Joints in Clay Masonry Spalled Faces
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Usually shrinkage in concrete masonry only a problem if restrained - NCMA T ek 10-1A, 10- 2C, 10-3.
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Control joints - creates a weakness in the masonry wall and allows the cracks to form in the joint NCMA Tek Note 10-2A
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Control joints - BOND BEAMS – need special detailing
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Use control joints with a minimum amount of reinforcing shown in Table 1 of NCMA Tek 10-2 C - based on experience may be adjusted
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Control Joints in Concrete Masonry Placement NCMA Tek Note 10-2A
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Concrete block and brick - different color
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Had control joints but too far apart. No cracking in dark CMU but cracking in lighter CMU
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Separate dissimilar materials
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Coping is very important ( joints need sealing) Movement of
add up and be the worst at coping May pop the coping and or roll over the parapet Recommend a flexible coping
joint & TWF
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Very important that joints go through all systems
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NCMA- TEK 6-1B
ICF From Web
Masonry Cavity Wall I was asked a while back whether you can design a high performance masonry wall – Like ICF The answer is yes !!!!!
Data from Sherman Carter Barnhart –Architects
Typical ICF system – R 23 – has an integral Air/moisture and vapor barrier – also structural ~ $31.4/SF (KY-values) Note - This is 16”+ thick wall If this ICF Wall defines high performance Can a masonry wall be designed to perform similarly? YES
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Try rigid insulation board in the cavity – Initially assume polyisocyanurate 3” Note the R value ranges from 24.3 to about 25.8 depending on the density of the materials and the temperature in the air space The air/vapor barrier on the masonry wall can be achieved by a spray-on mastic or trowel-on material behind the insulation Or – use foil faced insulation and taped seams – note that R value goes up to 25.8 to 28.3 with the foil facing in cavity.
R-Value =24.3
Spray or trowel-on air barrier or seal insulation seams
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8-in. concrete masonry backup wythe,grouted 48 in. o.c. vertically and 12 ft o.c. horizontally 3 in. polyisocyanurate rigid boardinsulation 1 in.airspace 4-in. clay brick veneer
Point- the insulation, air barrier, vapor barrier and moisture barrier protected in cavity
Try more conventional rigid insulation board in the cavity – Say assume 3.5”polyurethane, R ~22 Note if 3” of insulation is used R value ranges from 18.7 to about 19.8 depending on the density of the materials and the The air barrier on the masonry wall can be achieved by a spray
Spray on mastic will also form water/vapor barrier.
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12 in. extruded polystyrene temperature in the air space
rigid board insulation 8-in. concrete masonry backup wythe, grouted 48 in. o.c. vertically and 12 ft o.c. horizontally 1 in. airspace 4-in. clay brick veneer R-Value =21.7
Possible Spray or trowel-on barrier
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Point- the insulation, air barrier, vapor barrier and moisture barrier protected in cavity
OR - Try spray on closed cell Polyurethane foam Insulation
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Try 3” of spray foam insulation in the cavity – R-6.8/inch Note if 3” of insulation is used R value ranges from 23.4 to about 25.7 depending on the density
temperature in the air space The air/moisture/vapor barrier
contained in the insulation system
8-in. concrete masonry backup wythe, grouted 48 in. o.c. vertically and 12 ft o.c. horizontally 3 in. spray polyurethane foaminsulation 1 in.airspace 4-in. clay brickveneer R-Value = 23.4 64
SUS.TAINABLE DESIGN “DOING MORE WITH LESS” – OR AT LEAST DOING THE SAME WITH LESS Perhaps most effective walls have R 14 to 15 – (colder climates R)
R-V alue =14.2 8-in. concrete masonry backup wythe, grouted 48 in. o.c. vertically and 12 ft o.c.horizontally 2 in. extruded polystyrene rigid boardinsulation 1 in. airspace 4-in. clay brick veneer R-V alue =15.1 8-in. concrete masonry backup wythe, grouted 48 in. o.c. vertically and 12 ft o.c. horizontally 1.5 in. polyisocyanurate rigid boardinsulation 1 in. airspace 4-in. clay brick veneer
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R-Value =14.2 48 in. o.c. vertically and 12 ft o.c. horizontally 2 in. extruded polystyrene rigid board insulation 1 in.airspace 4-in. clay brick veneer
Studies at ORNL and elsewhere have shown the best performance in mass walls is obtained by putting the mass on the interior of the insulation
The mass on the interior of insulation and exposed to regulated temp helps mitigate interior temp variations and shifts peak loading – saves energy and peak
8-in. concrete masonry shaves –possible backup wythe, grouted thermal storage use
Insulating mass from interior allows internal loads to spike temps and reduces effect of mass – up to 5%
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Cost of this wall is approximately : $28.50/ft2 to 30.6/ft2 (KY values) Based on prevailing wages with spray-on air barrier
8-in. concrete masonry backup wythe,grouted 48 in. o.c. vertically and 12 ft o.c. horizontally 3 in. polyisocyanurate rigid boardinsulation 1 in. airspace 4-in. clay brick veneer R-Value =24.3
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12 in. extruded polystyrene
rigid board insulation 1 in. airspace 8-in. concrete masonry backup wythe, grouted 48 in. o.c. vertically and 12 ft o.c. horizontally 4-in. clay brick veneer
R-Value =21.7
Possible Spray or troweled barrier
Cost of this wall is approximately about the same $28.50/ft2 to 30.0/ft2 (KY Values) Based on prevailing wages with spray-on air barrier Remember ICF Cost ~$31.4/ft2
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Try 3” of spray foam insulation in the cavity – R-6.8/inch Cost of moisture/air barrier is about ~$1.10/ft2 and the cost of the 3” polyiso. insulation ~
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$2.50/ft so Spray insulation this is about the same cost as the polyiso. foil faced board.
8-in. concrete masonry backup wythe, grouted 48 in. o.c. vertically and 12 ft o.c. horizontally 3 in. spray polyurethane foaminsulation 1 in.airspace 4-in. clay brickveneer R-Value =23.4
Cost of Spay insulation – Generalvalues f 1.0 inches = R- 6.3 Budget $1.80/sq.ft. 1.5 inches = R- 9.45 Budget $2.20/sq.ft. 2.0 inches = R-12.60 Budget$2.80/sq.ft. 2.5 inches = R-15.75 Budget$3.40/sq.ft 3.0 inches = R-18.90 Budget $4.00/sq.ft With joint sealing and opening flashing– about $4- 6/ft2
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R-V alue =14.2 8-in. concrete masonry backup wythe, grouted 48 in. o.c. vertically and 12 ft o.c. horizontally 2 in. extruded polystyrene rigid boardinsulation 1 in. airspace 4-in. clay brick veneer
More conventional configuration should be closer to about $28.5/ft2 - $29 (KY Values)
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J.B. SPEED SCHOOL OF ENGINEERING
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